Phylogenetic Conservatism Research Articles

Isotopic niches do not follow the expectations of niche conservatism in the bird genus Cinclodes.

Phenotypic traits are expected to be more similar among closely related species than among species that diverged long ago (all else being equal). This pattern, known as phylogenetic niche conservatism, also applies to traits that are important to determine the niche of species. To test this hypothesis on ecological niches, we analysed isotopic data from 254 museum study skins from 12 of the 16 species of the bird genus Cinclodes and measured stable isotope ratios for four different elements: carbon, nitrogen, hydrogen and oxygen. We find that all traits, measured individually, or as a composite measurement, lack any phylogenetic signal, which in turn suggests a high level of lability in ecological niches. We compared these metrics to the measurements of morphological traits in the same genus and found that isotopic niches are uniquely evolutionarily labile compared to other traits. Our results suggest that, in Cinclodes, the realized niche evolves much faster than expected by the constraints of phylogenetic history and poses the question of whether this is a general pattern across the tree of life.

Interspecies trophic niche differences and spatial–temporal adaptations found in Cultrinae fishes

It has been debated whether interspecies niche differences may follow niche conservatism, whether niches are becoming specialists, whether generalists and specialists are maintained in a balance, and how the realized niche may adapt to local or temporal environments. In the present study, by using stable isotope analysis to evaluate the trophic niche of seven Cultrinae species, we investigated niche conservatism among these species from 10 sites of the Yangtze River by testing the Mantel test of trophic niche variables [trophic position (TP), δ13C, and trophic niche breadth]. We also comprehensively investigated the fundamental niche differences as well as spatial and temporal adaptations of the realized niche of these seven Cultrinae species by calculating trophic niche breadths, overlap, and TP. The results showed that TP and fundamental trophic niche breadth exhibited phylogenetic conservatism, while the fundamental trophic niche breadth of the three Hemicultrine species tended to become generalists and four Cultrine species tended to become specialists. Moreover, the realized trophic niche of the same species would exhibit different adaptation at different sites as well as in different seasons. In the wet season, trophic niche breadths of the seven species were significantly larger than that in the dry season with great overlaps between species, while in the dry season, trophic niche separation was found among the seven species due to competitive exclusion of niches. We believe that these findings will contribute to future theoretical and empirical niche investigations.

Climatic adaptation explains responses to Pleistocene oscillations and diversification in European vipers

AbstractAimAllopatric speciation is the primary mode of diversification in the Mediterranean Basin. However, the contribution of climatic adaptation during this process is contradictory. In this work, we investigate the eco‐evolutionary processes that drove diversification in this region, using European vipers as a case study. We describe the climatic requirements of different lineages to compare their responses to the Pleistocene climatic oscillations and tackle the evolutionary mechanisms underlying their diversification.LocationEurasia and North Africa.TaxonEuropean vipers (genus Vipera).MethodsWe used ecological niche modelling (ENM) to identify the climatic requirements of 24 Vipera lineages and infer past range dynamics associated with their diversification during the Pleistocene. To test whether climatic niches varied across lineages, we calculated the phylogenetic signal of different climatic variables and examined the relationship with phylogenetic relatedness. To investigate climatic niche evolution and test for phylogenetic niche conservatism (PNC), we quantified pairwise niche overlap in sister phylogenetic units under a 3D hypervolume approach.ResultsENM identified temperature annual range, precipitation of wettest month and precipitation of driest quarter as the most important climatic variables related to the distribution of most lineages, validating Pelias clade as cold‐adapted, and Vipera 1 and Vipera 2 as warm‐adapted clades. Projections to past conditions varied among clades, with Pelias and Vipera 1 having more similar responses, while Vipera 2 exhibited greater variability. We found significant phylogenetic signal in one temperature‐related and two humidity‐related climatic variables and detected high complexity in ecological niche evolution across the phylogeny, both rejecting the hypothesis of PNC.Main ConclusionsClimatic adaptation played a significant role in driving diversification among European vipers. Cold‐adapted and warm‐adapted lineages presented similar climatic requirements and remarkable responses to Pleistocene stages, resulting in an intricate pattern of niche divergence along the phylogeny that favours local adaptation rather than PNC.

Nutrient-cycling functional gene diversity mirrors phosphorus transformation during chicken manure composting

Elucidating ecological mechanism underlying phosphorus transformation mediated by phosphate-solubilizing bacteria (PSB) during manure composting is an important but rarely investigated subject. The research objective is to disentangle ecological functions of the inoculation of PSB Pseudomonas sp. WWJ-22 during chicken manure composting based on gene quantification and amplicon sequencing. There are large dynamic changes in phosphorus fractions, gene abundances, and bacterial community structure. The PSB addition notably increased available phosphorus from 0.29–0.89 g kg−1 to 0.49–1.39 g kg−1 and significantly affected phosphorus fractionation. The PSB inoculation significantly affected composition of nutrient-cycling functional genes (NCFGs), and notably influenced bacterial community composition and function. Compost bacteria showed significant phylogenetic signals in response to phosphorus fractions, and stochastic processes dominated bacterial community assembly. Results emphasized that PSB addition increased functional redundancy, phylogenetic conservatism, and stochasticity-dominated assembly of bacterial community. Overall, findings highlight NCFG diversity can be a bio-indicator to mirror phosphorus transformation.

Repeated asynchronous evolution of single‐species endemics of ivies (Hedera L.) in Macaronesian archipelagos

AbstractAimEvolutionary studies of oceanic island endemics are usually focused on lineages that have experienced in situ radiation, while those that speciated once on the island or archipelago but have not further diversified (single‐species endemics) remain understudied. The Macaronesian archipelagos, in the Atlantic Ocean, are home to significant numbers of single‐species endemics. The genus Hedera L. (12 species) includes three single‐species endemics from three Macaronesian archipelagos with putatively independent origins. Here, we tested the role of phylogenetic niche conservatism in their evolution. To that end, we (1) reconstructed the spatio‐temporal origin of Macaronesian ivies using phylogenomics, and (2) assessed the role of climatic niche during their colonization and speciation.LocationAzores, Canary Islands, Madeira, western Mediterranean.TaxonHedera spp.MethodsWe used 166 samples representing all Hedera species to generate genotyping‐by‐sequencing (GBS) libraries and performed time‐calibrated phylogenomic and biogeographic analyses. Climatic preferences and climatic niche evolution were assessed using a geo‐referenced database of the western ivy species (2,297 records).ResultsIndependent and asynchronous colonization and speciation were estimated for the three Macaronesian ivies, resulting in different degrees of phylogenetic and climatic niche differentiation: H. canariensis displayed an early divergence (7.5–12 Ma) and high phylogenetic and niche isolation; H. azorica had intermediate phylogenetic isolation and niche divergence from its closest relative H. helix (4.4–6.8 Ma) and H. maderensis was embedded within the climatically similar H. iberica (2.8–4.6 Ma). A strong phylogenetic signal was suggested for climatic niche in the western clade of Hedera, where the three Macaronesian ivies are placed.Main ConclusionsThe three Macaronesian ivies represent the evolutionary stages leading to the emergence of single‐species island endemics. Climatic niche conservatism appears to be involved in the evolution of single‐species endemics, first by facilitating island colonization, and then by limiting in situ diversification.

Inter- and intraspecific adaptations of pteridophyte leaf traits in limestone and non-limestone forests of monsoon tropical regions of southwest China

Abstract Plant species often show different taxonomic and functional characteristics between limestone forests (LFs) and non-limestone forests (NLFs) in tropical regions. Pteridophyte species are one of the major components in tropical rainforests; however, the morphological and physiological characteristics of pteridophytes occurring in LFs are poorly understood. We evaluated the differences in seven leaf functional traits between pteridophyte species in LFs and NLFs in southwest China. We measured leaf water content, morphological traits including leaf size, leaf thickness, stomatal length and stomatal density (SD), and physiological traits including stomatal conductance and photosynthetic rate from a total of 25 species. We found that pteridophytes had thicker and smaller leaves with lower SD and stomatal conductance in LFs compared with NLFs, probably reflecting their adaptations in water use strategies. These differences, however, became non-significant when phylogenetic relationships were taken into account, suggesting that phylogenetic conservatism shapes trait differences and ultimately species composition in LFs and NLFs. Some species that were commonly found in both LFs and NLFs exhibited intraspecific variation between forest types, with lower SD in LFs. Our findings suggest that only a handful of pteridophyte species can adapt to their water use strategies in both LFs and NLFs, and thus adaptative radiation is unlikely to occur.

Species phylogeny, ecology, and root traits as predictors of root exudate composition.

Root traits including root exudates are key factors affecting plant interactions with soil and thus play an important role in determining ecosystem processes. The drivers of their variation, however, remain poorly understood. We determined the relative importance of phylogeny and species ecology in determining root traits and analyzed the extent to which root exudate composition can be predicted by other root traits. We measured different root morphological and biochemical traits (including exudate profiles) of 65 plant species grown in a controlled system. We tested phylogenetic conservatism in traits and disentangled the individual and overlapping effects of phylogeny and species ecology on traits. We also predicted root exudate composition using other root traits. Phylogenetic signal differed greatly among root traits, with the strongest signal in phenol content in plant tissues. Interspecific variation in root traits was partly explained by species ecology, but phylogeny was more important in most cases. Species exudate composition could be partly predicted by specific root length, root dry matter content, root biomass, and root diameter, but a large part of variation remained unexplained. In conclusion, root exudation cannot be easily predicted based on other root traits and more comparative data on root exudation are needed to understand their diversity.

Weak latitudinal trends in reproductive traits of Afromontane forest trees.

Is the increase in species diversity patterns towards lower latitudes linked to reproductive traits? Plant reproductive organs influence reproductive isolation and hence species divergence. Abiotic differences between temperate and tropical regions can also directly impact on plant reproductive traits. Here we provide a novel overview of southern hemisphere, Afromontane forest tree taxonomical patterns and ask whether reproductive traits relate to latitude, while accounting for environmental (tree height) and evolutionary (biogeographical affinity) selective forces. We compiled a novel dataset with (1) flower colour, size and pollination syndrome and (2) fruit colour, size and dispersal syndrome for 331 tree species found in six Afromontane forest regions. We categorized each species into latitudinal distribution using these six regions, spanning the southern Cape (34º S) to Mount Kenya (0º S). Additionally, we gathered maximum tree height (m) for each species and determined the global distribution of all 196 tree genera (Afrotropical, Palaeotropical or Pantropical). Species, genera and families showed a general decrease in richness away from tropical and subtropical forests towards warm temperate forests. Southern Afrotemperate forests (the furthest south) had the highest tree endemism. There was no relationship between latitude and the reproductive traits tested here. Biogeographical affinity related to fruit colour and dispersal syndrome, with palaeotropical genera showing relative increases in black-purple fruit colour compared with pantropical genera, and palaeotropical genera showing relative increases in biotic seed dispersal compared with Afrotropical genera, which showed higher relative abiotic seed dispersal. Taller trees had a higher chance to be wind or insect pollinated (compared with bird pollinated) and had larger fruits. Latitude explained patterns in Afromontane tree taxonomic diversity; however, tree reproductive traits did not relate to latitude. We suggest that phylogenetic conservatism or convergence, or both, explain the reported patterns.

Mechanisms of equality and inequality in mammalian societies.

The extent of (in)equality is highly diverse across species of social mammals, but we have a poor understanding of the factors that produce or inhibit equitable social organizations. Here, we adopt a comparative evolutionary perspective to test whether the evolution of social dominance hierarchies, a measure of social inequality in animals, exhibits phylogenetic conservatism and whether interspecific variation in these traits can be explained by sex, age or captivity. We find that hierarchy steepness and directional consistency evolve rapidly without any apparent constraint from evolutionary history. Given this extraordinary variability, we next consider multiple factors that have evolved to mitigate social inequality. Social networks, coalitionary support and knowledge transfer advantage to privilege some individuals over others. Nutritional access and prenatal stressors can impact the development of offspring, generating health disparities with intergenerational consequences. Intergenerational transfer of material resources (e.g. stone tools, food stashes, territories) advantage those who receive. Nonetheless, many of the same social species that experience unequal access to food (survival) and mates (reproduction) engage in levelling mechanisms such as food sharing, adoption, revolutionary coalitions, forgiveness and inequity aversion. Taken together, mammals rely upon a suite of mechanisms of (in)equality to balance the costs and benefits of group living. This article is part of the theme issue 'Evolutionary ecology of inequality'.

Phylogenetically conservative trait correlation: Quantification and interpretation

Abstract Correlation across species between two quantitative traits, or between a trait and a habitat property, can suggest that a trait value is effective in sustaining populations in some contexts but not others. It is widely held that such correlations should be controlled for phylogeny, via phylogenetically independent contrasts (PICs) or phylogenetic generalized least squares (PGLS). A weakness of this idea is that a clade's traits tend to confer success in particular habitats or ways of life, and those niches in turn tend to select for the same traits to continue in the clade. This feedback mechanism can bind phylogeny and niche together as a unified cause for present‐day trait configurations. Accordingly, the phylogenetically conservative share of a trait correlation ought not to be excluded from consideration as potentially ecologically functional. Another weakness is that PGLS does not yield a complete or accurate breakdown of covariation between traits A and B because it corresponds to a generating model where B predicts variation in A but not the reverse, and phylogenetic signal in B is not modelled. Multi‐response mixed models using phylogenetic covariance matrices can quantify conservative trait correlation (CTC), a share of A‐B covariation that is phylogenetically conservative. Because the evidence is from correlative data, it is not possible to split CTC into causation by phylogenetic history versus causation by continuing reciprocal selection between A and B. Moreover, it is quite likely biologically that the two influences have acted in concert, through phylogenetic niche conservatism. Synthesis: The CTC concept treats phylogenetic conservatism as a conjoint interpretation alongside ongoing influence of other traits. CTC can be quantified via multi‐response phylogenetic mixed models.

Niche conservatism over deep timescales and diverse niche axes in land vertebrates

AbstractAimThere has been considerable interest in niche conservatism, the idea that ecological variables are similar among related species. Much research has focused on climatic niches of recently diverged species, rather than deeper timescales or non‐climatic niche axes. Furthermore, it has been suggested that conservatism disappears over deeper timescales, and is greater in alpha niche traits (like diet and microhabitat) than beta niche variables (like climate). Here, we test these latter two ideas by comparing patterns of phylogenetic conservatism among 10 niche variables across major clades of land vertebrates.LocationGlobal.Time PeriodPresent to 350 million years ago.Major Taxa StudiedTetrapods, including amphibians, mammals, lepidosaurs (including lizards and snakes), turtles, crocodilians and birds.MethodsThe 10 niche variables included four alpha niche components (diet, diel activity, habitat, body temperature) and six beta niche components (related to climatic temperature and precipitation). We analysed these variables on time‐calibrated phylogenies with similar taxon sampling (~1700 species), using phylogenetic signal (lambda) to estimate conservatism, along with the D statistic and estimates of evolutionary rates.ResultsPhylogenetic signal was generally strong across all variables, with lambda generally >0.80 (with 1.0 representing maximum signal). Nevertheless, mean phylogenetic signal was lower in beta niche traits than alpha niche traits (based on lambda and especially the D statistic), and alpha niche traits showed significantly slower rates of evolution.Main ConclusionsWe address two long‐held views in the literature on niche conservatism, rejecting one but supporting the other. We show that phylogenetic signal does not disappear over deep timescales for many important niche variables, even over 350 million years. We also generally support greater conservatism in alpha niche traits than beta niche traits over hundreds of millions of years, a pattern that was previously suggested (but not explicitly tested) based on closely related species.

Weak phylogenetic and habitat effects on root trait variation of 218 Neotropical tree species

IntroductionTropical forests harbor a large diversity of closely related tree species that can thrive across habitats. This biodiversity has been found to correspond to large functional diversity in aboveground traits, and likely also relates to belowground trait variation. Globally, root trait (co-)variation is driven by different belowground resource strategies of species, environmental variation, and phylogeny; however, these patterns mostly reflect observations from temperate biomes and remain unconfirmed in tropical trees. We examine phylogenetic and environmental effects on root trait (co-)variation of trees across habitats in an Amazonian rainforest.MethodsRoots of 218 tree species from ten dominant families were sampled across three major habitats near Manaus, Brazil. We quantified five morphological and architectural root traits to (i) investigate how they reflected different resource strategies across species, (ii) compare them between families and superorders to test phylogenetic effects, and (iii) compare them between habitats to determine environmental effects on root trait expressions and variability.ResultsRoot traits discriminated species along a tradeoff between root diameter and root branching and, secondly, due to variation in root tissue density. Our results further show weak phylogenetic effects on tropical tree root variation, for example, families from the same superorder showed large divergence in their root traits, while those from different superorders often overlapped in their root morphology and architecture. Root traits differed significantly between habitats but habitat type had only little effect on overall root trait variation.DiscussionOur work suggests that the dimensions and drivers that underlie (co-)variation in tropical root traits may differ from global patterns defined by mostly temperate datasets. Due to (a)biotic environmental differences, different root trait dimensions may underlie the belowground functional diversity in (Neo)tropical forests, and we found little evidence for the strong phylogenetic conservatism observed in root traits in temperate biomes. We highlight important avenues for future research on tropical roots in order to determine the degree of, and shifts in functional diversity belowground as communities and environments change in tropical forests.

The role of phylogenetic relatedness on success of non‐native plants crossing the naturalization–invasion transition in North America

Understanding the causes and consequences of biological invasions is a great challenge in ecology and conservation biology. The ability to predict which naturalized species are likely to become invasive would be a great step forward in managing and preventing invasions. The goal of this study is to test whether invasive species are a phylogenetically clustered subset of naturalized species at continental and regional scales, and to compare phylogenetic relatedness of invasive angiosperms with respect to species pools of non‐native naturalized angiosperms in North America. We divided North America into 65 state‐ or province‐level regions, and collated naturalized and invasive species lists of angiosperms for each region. Two phylogenetic metrics (net relatedness index (NRI) and nearest taxon index (NTI)), which represent different evolutionary depths, were used to quantify phylogenetic relatedness of naturalized and invasive angiosperms in North America, with respect to different species pools. We related phylogenetic relatedness of invasive angiosperms to climatic variables. We found that most invasive angiosperm assemblages are a phylogenetically clustered subset of their respective naturalized species pools, and the phylogenetic clustering of invasive species is greater in regions with lower temperature and precipitation. The pattern of phylogenetic clustering of invasive species likely reflects phylogenetic conservatism of traits associated with invasiveness. It may also reflect a tendency towards greater invasiveness for species with novel trait combinations compared to the non‐invasive naturalized species assemblages.

Range restricted old and young lineages show the southern Western Ghats to be both a museum and a cradle of diversity for woody plants.

The Western Ghats (WG) mountain chain is a global biodiversity hotspot with high diversity and endemicity of woody plants. The latitudinal breadth of the WG offers an opportunity to determine the evolutionary drivers of latitudinal diversity patterns. We examined the spatial patterns of evolutionary diversity using complementary phylogenetic diversity and endemism measures. To examine if different regions of the WG serve as a museum or cradle of evolutionary diversity, we examined the distribution of 470 species based on distribution modelling and occurrence locations across the entire region. In accordance with the expectation, we found that the southern WG is both a museum and cradle of woody plant evolutionary diversity, as a higher proportion of both old and young evolutionary lineages are restricted to the southern WG. The diversity gradient is likely driven by high geo-climatic stability in the south and phylogenetic niche conservatism for moist and aseasonal sites. This is corroborated by persistent lineage nestedness at almost all evolutionary depths (10-135 million years), and a strong correlation of evolutionary diversity with drought seasonality, precipitation and topographic heterogeneity. Our results highlight the global value of the WG, demonstrating, in particular, the importance of protecting the southern WG-an engine of plant diversification and persistence.

Effect of Host-Switching on the Ecological and Evolutionary Patterns of Parasites.

Speciation via host-switching is a macroevolutionary process that emerges from a microevolutionary dynamic where individual parasites switch hosts, establish a new association, and reduce reproductive contact with the original parasite lineage. Phylogenetic distance and geographic distribution of the hosts have been shown to be determinants of the capacity and opportunity of the parasite to change hosts. Although speciation via host-switching has been reported in many host-parasite systems, its dynamic on the individual, population and community levels is poorly understood. Here we propose a theoretical model to simulate parasite evolution considering host-switching events on the microevolutionary scale, taking into account the macroevolutionary history of the hosts, to evaluate how host-switching can affect ecological and evolutionary patterns of parasites in empirical communities at regional and local scales. In the model, parasite individuals can switch hosts under variable intensity and have their evolution driven by mutation and genetic drift. Mating is sexual and only individuals that are sufficiently similar can produce offspring. We assumed that parasite evolution occurs at the same evolutionary time scale as their hosts, and that the intensity of host-switching decreases as the host species differentiate. Ecological and evolutionary patterns were characterized by the turnover of parasite species among host species, and parasite evolutionary tree imbalance respectively. We found a range of host-switching intensity that reproduces ecological and evolutionary patterns observed in empirical communities. Our results showed that turnover decreased as host-switching intensity increased, with low variation among the model replications. On the other hand, tree imbalance showed wide variation and non-monotonic tendency. We concluded that tree imbalance was sensitive to stochastic events, whereas turnover may be a good indicator of host-switching. We found that local communities corresponded to higher host-switching intensity when compared to regional communities, highlighting that spatial scale is a limitation for host-switching. [Dispersal of parasites, opportunity and capacity of interaction, phylogenetic conservatism, and community structure.].

Nutrient‐based species selection is a prevalent driver of community assembly and functional trait space in tropical forests

AbstractSoil nutrient availability and functional traits interact in complex ways during the assembly of tree communities hindering our understanding of the implications that this may have for their phylogenetic and functional diversity.We combined abundance, taxonomic, phylogenetic and functional trait data of 222 tree species distributed along nutrient concentration gradients at 24 plots in two tropical forest study sites. We analysed micro and macronutrient concentration in organic and topsoil horizons and tested for the following: (1) nutrient‐based species sorting due to contrasting trait–environment relationships, (2) whether nutrient filtering has consequences for phylogenetic and functional diversity, and functional space size and occupancy and (3) we mapped trait distributions across the phylogeny of tree species to track the evolutionary signature of nutrient availability.We found that total nitrogen (N), available phosphorus and total potassium in soil accounted for 68% of the variation in tropical tree species community composition, with strong associations with nutrient concentration for 89% of the tree species included in the analysis. This nutrient‐based species selection was mediated by interactions between the three soil nutrient concentrations with leaf nitrogen, leaf thickness and wood density. Soil N concentration was positively associated with the functional space at site level. At plot level, soil N concentration positively correlated with functional evenness and it was negatively associated with the functional space not occupied by any species in the tree community. Despite the phylogenetic conservatism of leaf N across tree lineages even when not considering legumes, many sister‐species pairs show contrasting values which match with their habitat preferences thus indicating the evolutionary lability of this trait, particularly within recently diversified clades.Synthesis. Our results demonstrate that soil nutrient‐based species selection is a prevalent driver of community assembly in tropical forests, a process mediated by key functional traits within the leaf and wood economics spectrum. Functional space size and its filling increase with soil nutrient concentration, whereas niche vacancy decreases. This selection process has likely influenced tropical tree species diversification patterns via habitat specialization.

Genome size variation and polyploidy prevalence in the genus Eragrostis are associated with the global dispersal in arid area.

Biologists have long debated the drivers of the genome size evolution and variation ever since Darwin. Assumptions for the adaptive or maladaptive consequences of the associations between genome sizes and environmental factors have been proposed, but the significance of these hypotheses remains controversial. Eragrostis is a large genus in the grass family and is often used as crop or forage during the dry seasons. The wide range and complex ploidy levels make Eragrostis an excellent model for investigating how the genome size variation and evolution is associated with environmental factors and how these changes can ben interpreted. We reconstructed the Eragrostis phylogeny and estimated genome sizes through flow cytometric analyses. Phylogenetic comparative analyses were performed to explore how genome size variation and evolution is related to their climatic niches and geographical ranges. The genome size evolution and environmental factors were examined using different models to study the phylogenetic signal, mode and tempo throughout evolutionary history. Our results support the monophyly of Eragrostis. The genome sizes in Eragrostis ranged from ~0.66 pg to ~3.80 pg. We found that a moderate phylogenetic conservatism existed in terms of the genome sizes but was absent from environmental factors. In addition, phylogeny-based associations revealed close correlations between genome sizes and precipitation-related variables, indicating that the genome size variation mainly caused by polyploidization may have evolved as an adaptation to various environments in the genus Eragrostis. This is the first study to take a global perspective on the genome size variation and evolution in the genus Eragrostis. Our results suggest that the adaptation and conservatism are manifested in the genome size variation, allowing the arid species of Eragrostis to spread the xeric area throughout the world.

Gynoecium structure and pollen tube pathway in the cactus family with emphasis on tribe Trichocereeae (Cactaceae: Cactoideae)

Abstract The structural details of the gynoecium are key to understanding the reproductive systems and successful diversification of flowering plants. However, the gynoecium morpho-anatomy in South American species of Cactaceae that evolved in the Andean region remains largely unknown. Here we selected 18 species, most of them of evolutionarily related genera of Cactaceae tribe Trichocereeae, to conduct a detailed comparative study. Observations were made using light, fluorescence, differential interference contrast and scanning electron microscopy. Most of the characters of the ovary and ovule were typical of the family, except for the nucellar beak in Echinopsis aurea and E. haematantha, here reported for the first time in cacti. We found evidence suggesting that the stigmatic surface covered with multiseriate trichomes, the semi-closed style type and the pollen tube transmitting tract are conserved characters among species of Trichocereeae; this finding may be explained by a phylogenetic conservatism of the investigated genera of the tribe. We integrated the available information about structural and histological characters of the gynoecium in the family, taking into account the current phylogenetic context of the examined genera. Our results reinforce the significance of floral anatomical traits for the systematics of Cactaceae.

Precipitation is the main axis of tropical plant phylogenetic turnover across space and time.

Early natural historians-Comte de Buffon, von Humboldt, and De Candolle-established environment and geography as two principal axes determining the distribution of groups of organisms, laying the foundations for biogeography over the subsequent 200 years, yet the relative importance of these two axes remains unresolved. Leveraging phylogenomic and global species distribution data for Mimosoid legumes, a pantropical plant clade of c.3500 species, we show that the water availability gradient from deserts to rain forests dictates turnover of lineages within continents across the tropics. We demonstrate that 95% of speciation occurs within a precipitation niche, showing profound phylogenetic niche conservatism, and that lineage turnover boundaries coincide with isohyets of precipitation. We reveal similar patterns on different continents, implying that evolution and dispersal follow universal processes.

Geographic distribution and climatic niche comparison between diploid and polyploid cytotypes of a South American genus Lessingianthus H.Rob. (Vernonieae, Asteraceae)

The distribution of ploidy levels and their ecological associations were studied using the genus Lessingianthus (Vernonieae, Asteraceae) as a model system. This genus is very complex from a cytogenetic point of view, with high cytotype diversity at the interspecific and intraspecific levels and with a continuous distribution throughout South America. So far, no previous studies have summarized chromosome count data for Lessingianthus or addressed the cytogeography of the genus. In this study, the ploidy levels of Lessingianthus species were determined by chromosome counts during mitosis and ecological niche modelling (ENM) was used to compare the environmental associations of the diploid and polyploid cytotypes. In total, 28 chromosome counts and six ploidy levels (2x, 4x, 6x, 8x, 10x, and 11x) were recorded. Among these counts, the chromosome numbers for three hexaploids with 2 n = 96 (L. parvifolius, L. vepretorum and L. “bolivianensis” sp. ined.) and one decaploid taxon with 2 n = 160 (L. roseus) were reported for the first time. In addition, a new cytotype for L. laniferus (2 n = 6x = 96) was also reported. The cytogeographic analysis resulted in detecting two geographic zones with high diversity of cytotypes and species. The ENMs showed that the areas of climatic suitability of diploids and polyploids are similar in extent, as well as the climatic requirements, showing high values of niche overlap within the environmental space. Our findings suggested that polyploidization in Lessingianthus has not caused expansion to novel environmental conditions and phylogenetic niche conservatism (PNC) may explain the lack of niche differentiation between diploids and polyploids.