Ancestral Ecology Research Articles

The origin of human pathogenicity and biological interactions in Chaetothyriales

Fungi in the order Chaetothyriales are renowned for their ability to cause human infections. Nevertheless, they are not regarded as primary pathogens, but rather as opportunists with a natural habitat in the environment. Extremotolerance is a major trend in the order, but quite different from black yeasts in Capnodiales which focus on endurance, an important additional parameter is advancing toxin management. In the ancestral ecology of rock colonization, the association with metabolite-producing lichens is significant. Ant-association, dealing with pheromones and repellents, is another mainstay in the order. The phylogenetically derived family, Herpotrichiellaceae, shows dual ecology in monoaromatic hydrocarbon assimilation and the ability to cause disease in humans and cold-blooded vertebrates. In this study, data on ecology, phylogeny, and genomics were collected and analyzed in order to support this hypothesis on the evolutionary route of the species of Chaetothyriales. Comparing the ribosomal tree with that of enzymes involved in toluene degradation, a significant expansion of cytochromes is observed and the toluene catabolism is found to be complete in some of the Herpotrichiellaceae. This might enhance human systemic infection. However, since most species have to be traumatically inoculated in order to cause disease, their invasive potential is categorized as opportunism. Only in chromoblastomycosis, true pathogenicity might be surmised. The criterion would be the possible escape of agents of vertebrate disease from the host, enabling dispersal of adapted genotypes to subsequent generations.

Horizontal Transposon Transfer and Its Implications for the Ancestral Ecology of Hydrophiine Snakes.

Transposable elements (TEs), also known as jumping genes, are sequences able to move or copy themselves within a genome. As TEs move throughout genomes they often act as a source of genetic novelty, hence understanding TE evolution within lineages may help in understanding environmental adaptation. Studies into the TE content of lineages of mammals such as bats have uncovered horizontal transposon transfer (HTT) into these lineages, with squamates often also containing the same TEs. Despite the repeated finding of HTT into squamates, little comparative research has examined the evolution of TEs within squamates. Here we examine a diverse family of Australo–Melanesian snakes (Hydrophiinae) to examine if the previously identified, order-wide pattern of variable TE content and activity holds true on a smaller scale. Hydrophiinae diverged from Asian elapids ~30 Mya and have since rapidly diversified into six amphibious, ~60 marine and ~100 terrestrial species that fill a broad range of ecological niches. We find TE diversity and expansion differs between hydrophiines and their Asian relatives and identify multiple HTTs into Hydrophiinae, including three likely transferred into the ancestral hydrophiine from fish. These HTT events provide the first tangible evidence that Hydrophiinae reached Australia from Asia via a marine route.

Horizontal transposon transfer and its implications for the ancestral ecology of hydrophiine snakes

Horizontal transposon transfer and its implications for the ancestral ecology of hydrophiine snakes

Ecological aspects of regulation of the plasticity of accumulation of terpene compounds in plants

Field mint (Mentha arvensis L.) of the Mentha (Lamiaceae) is one of the most important species among medicinal and essential oil-bearing plant. The content of essential oils in the plants of field mint M. arvensis was studied depending on the growing conditions in three biocoenoses, taking into account the increase in soil moisture availability. The output of essential oil from the aboveground part of mint plants was maximum during the mass flowering phase and amounted to 2.7±0.08% in mesohydrophytic biocoenoses, 2.3±0.09% in mesophytic and 1.3±0.11% in xeromesophytic biocoenoses. Cyclic terpenes and terpenoids (65.2 and 59.8%, respectively) predominated in the composition of the field mint plants oil of mesohydrophytic and mesophytic biocoenoses, the soil moisture content of which is more consistent with the mesophilic ancestral ecology of the species, while acyclic compounds accounted for 31.2 and 34.6 %. Simpler acyclic terpenes and terpenoids dominated in the field mint oil profile of xeromesophytic biocoenoses (55.3%). The essential oil of mint plants of all three ecological biocoenoses contained terpenes with a pronounced protective function -α- terpinene, γ-terpinolen, trans and cis-ocimene, eucalyptol (1,8 cineol), which exhibit broad antimicrobial and insecticidal properties. The concentration of these compounds was maximal in plants of the xeromesophytic biocoenoses. While the maximum content of volatile terpenes (β-myrcene, cis-geraniol, nerol acetate), which perform an attractive function (ensures the relationship of plants with insects), is recorded in the mesohydrophytic biocoenoses. The adaptation of mint plants to different ecological conditions is ensured by the shift in the activity of secondary metabolism towards increasing the synthesis of simpler in structure and less energy-intensive components, which provides the population with a selective advantage as the species moves to new habitats that differ in ecological conditions from those specific to ancestral forms.

Isotopic paleoecology of Northern Great Plains bison during the Holocene

Bison (Bison bison) are one of the few terrestrial megafauna to survive the transition into the Holocene and provide a unique opportunity to study a species on a broad spatiotemporal scale. Today, bison are primarily managed in small and isolated herds with little known about their ancestral ecology. We studied the carbon and nitrogen isotopes of Northern Great Plains bison from the terminal Pleistocene and throughout the Holocene to gain insight into their paleoecology. This time span is contemporary with the first population bottleneck experienced by bison at the end of the Pleistocene and includes the second bottleneck which occurred in the late 19th century. Results were compared with modern bison herd isotopic values from Theodore Roosevelt National Park (TRNP). Patterns of isotopic variation found in bison over time indicate significant (δ13C p = 0.0008, δ15N p = 0.002) differences in diet composition and correlate with climate throughout the Holocene. Isotopic relationships described here reveal the plasticity of ancient bison in unrestricted rangelands during periods of climatic fluctuations. Managers at TRNP and elsewhere should pursue opportunities to expand bison range to maximize forage opportunities for the species in the face of future environmental change.

Staying cool: preadaptation to temperate climates required for colonising tropical alpine-like environments.

Plant species tend to retain their ancestral ecology, responding to temporal, geographic and climatic changes by tracking suitable habitats rather than adapting to novel conditions. Nevertheless, transitions into different environments or biomes still seem to be common. Especially intriguing are the tropical alpine-like areas found on only the highest mountainous regions surrounded by tropical environments. Tropical mountains are hotspots of biodiversity, often with striking degrees of endemism at higher elevations. On these mountains, steep environmental gradients and high habitat heterogeneity within small spaces coincide with astounding species diversity of great conservation value. The analysis presented here shows that the importance of in situ speciation in tropical alpine-like areas has been underestimated. Additionally and contrary to widely held opinion, the impact of dispersal from other regions with alpine-like environments is relatively minor compared to that of immigration from other biomes with a temperate (but not alpine-like) climate. This suggests that establishment in tropical alpine-like regions is favoured by preadaptation to a temperate, especially aseasonal, freezing regime such as the cool temperate climate regions in the Tropics. Furthermore, emigration out of an alpine-like environment is generally rare, suggesting that alpine-like environments – at least tropical ones – are species sinks.

Parent-offspring conflict and the evolution of infant-directed song

We present a theory of the origin and evolution of infant-directed song, a form of music found in many cultures. After examining the ancestral ecology of parent-infant relations, we propose that infant-directed song arose in an evolutionary arms race between parents and infants, stemming from the dynamics of parent-offspring conflict. We describe testable predictions that follow from this theory, consider some existing evidence for them, and entertain the possibility that infant-directed song could form the basis for the development of other, more complex forms of music.

Evolutionary conservatism and convergence both lead to striking similarity in ecology, morphology and performance across continents in frogs

Many clades contain ecologically and phenotypically similar species across continents, yet the processes generating this similarity are largely unstudied, leaving fundamental questions unanswered. Is similarity in morphology and performance across assemblages caused by evolutionary convergence or by biogeographic dispersal of evolutionarily conserved ecotypes? Does convergence to new ecological conditions erase evidence of past adaptation? Here, we analyse ecology, morphology and performance in frog assemblages from three continents (Asia, Australia and South America), assessing the importance of dispersal and convergent evolution in explaining similarity across regions. We find three striking results. First, species using the same microhabitat type are highly similar in morphology and performance across both clades and continents. Second, some species on different continents owe their similarity to dispersal and evolutionary conservatism (rather than evolutionary convergence), even over vast temporal and spatial scales. Third, in one case, an ecologically specialized ancestor radiated into diverse ecotypes that have converged with those on other continents, largely erasing traces of past adaptation to their ancestral ecology. Overall, our study highlights the roles of both evolutionary conservatism and convergence in explaining similarity in species traits over large spatial and temporal scales and demonstrates a statistical framework for addressing these questions in other systems.

The evolution of substrate differentiation in Minuartia series Laricifoliae (Caryophyllaceae) in the European Alps: In situ origin or repeated colonization?

Substrate specialization is often considered an important factor in evolutionary diversification. A classic example of divergence related to different substrate types is the dichotomy between calcicole and calcifuge plants on calcareous and siliceous substrates as found in the European Alps. When closely related species with contrasting substrate preferences are found in the same area, it is generally hypothesized that they diverged where they now occur. However, it is possible that Alpine edaphic diversity instead allows the coexistence of related species whose edaphic differentiation took place deeper in the phylogeny, in some other part of the range of their clades. We used sequences of the nuclear internal and external transcribed spacer regions to examine the origin of substrate differentiation in Minuartia series Laricifoliae, which contains many edaphic endemics, including a pair of Alpine taxa with contrasting substrate preferences: Minuartia langii (calcicole) and M. laricifolia (calcifuge). MINUARTIA LANGII and M. laricifolia are each more closely related to Balkan species than they are to each other and reached the Alps independently. The clade to which they belong is ancestrally calcicole. Minuartia langii inherited the ancestral ecology, while M. laricifolia is part of a subclade with serpentine endemics and one substrate generalist. In the study group, taxa with contrasting substrate preferences did not diverge in the Alps. Instead, taxa whose substrate differentiation arose elsewhere, likely on the Balkan Peninsula, were preadapted to take advantage of Alpine substrate diversity.

Beak and skull shapes of human commensal and non-commensal house sparrows Passer domesticus

BackgroundThe granivorous house sparrow Passer domesticus is thought to have developed its commensal relationship with humans with the rise of agriculture in the Middle East some 10,000 years ago, and to have expanded with the spread of agriculture in Eurasia during the last few thousand years. One subspecies, P. d. bactrianus, residing in Central Asia, has apparently maintained the ancestral ecology, however. This subspecies is not associated with human settlements; it is migratory and lives in natural grass- and wetland habitats feeding on wild grass seeds. It is well documented that the agricultural revolution was associated with an increase in grain size and changes in seed structure in cultivated cereals, the preferred food source of commensal house sparrow. Accordingly, we hypothesize that correlated changes may have occurred in beak and skull morphology as adaptive responses to the change in diet. Here, we test this hypothesis by comparing the skull shapes of 101 house sparrows from Iran, belonging to five different subspecies, including the non-commensal P. d. bactrianus, using geometric morphometrics.ResultsThe various commensal house sparrow subspecies share subtle but consistent skeletal features that differ significantly from those of the non-commensal P. d. bactrianus. Although there is a marked overall size allometry in the data set, the shape difference between the ecologically differentiated sparrows cannot be explained by differences in size alone. Relative to the size allometry commensal house sparrows exhibit a skull shape consistent with accelerated development (heterochrony), resulting in a more robust facial cranium and a larger, more pointed beak.ConclusionThe difference in skull shape and robustness of the beak between commensal and non-commensal house sparrows is consistent with adaptations to process the larger and rachis encapsulated seeds of domesticated cereals among human associated populations.

Asian origin and upslope migration of Hawaiian Artemisia (Compositae–Anthemideae)

AbstractAimMajor habitat shifts are well documented for the Hawaiian flora, but examples of shifts to the highest Hawaiian habitats by plant lineages of lowland tropical ancestry have been lacking. We sought to determine whether Hawaiian Artemisia (Compositae–Anthemideae), which includes lowland and subalpine species, represents such an example, by investigating the origin and relationships of the Hawaiian taxa.LocationHawaiian Islands and continental settings world‐wide (except Antarctica and Australia).MethodsMolecular phylogenetic analyses of Hawaiian Artemisia in the context of world‐wide diversity were conducted using nuclear and chloroplast DNA spacers. The timing of divergence events associated with inferred dispersals was estimated with calibration from fossil pollen records. Historical biogeographical analyses based on molecular trees and ecological modelling of the distributions of extant taxa were used to aid the interpretation of geographical and habitat shifts associated with diversification and long‐distance dispersal.ResultsOur findings indicate that the Hawaiian endemic species (A. australis, A. kauaiensis and A. mauiensis) constitute a clade sister to Southeast Asian A. chinensis, which, like the Hawaiian endemics, has ribbed fruit walls and, unlike other members of Artemisia except A. kauaiensis, has a distinct pappus, which is often associated with dispersal ability in Compositae. The clade encompassing A. chinensis and Hawaiian Artemisia was resolved to be most likely of Asian origin. The natural occurrence of A. chinensis in littoral habitats of Taiwan, Okinawa, and the Ryukyu and Bonin islands, and of A. australis in similar settings in the Hawaiian Islands, is likely to reflect the ancestral ecology of the Hawaiian clade, with subsequent colonization of inland, higher‐elevation habitats, including subalpine shrubland, where A. mauiensis is endemic.Main conclusionsAn ecological shift in Hawaiian Artemisia from tropical coastal habitats to drier and colder subalpine slopes is consistent with evidence from recent studies for repeated colonization of the Arctic by diverse lineages of Artemisia. Artemisia appears to be prone to such anticlimatic ecological shifts, which may explain this exceptional example of an ancestrally lowland tropical lineage in the Hawaiian high‐montane flora.

Inferring biogeographic history from molecular phylogenies

The present study illustrates a method for analysing the biogeography of a group that is based on the group’s phylogeny but does not invoke founder dispersal or centre of origin. The case studies presented include groups from many different parts of the world, but most are from the south-west Pacific. The idea that basal groups are ancestral is not valid as a generalization. Neither the basal group, nor the oldest fossil represents the centre of origin, the time of origin or the ancestral ecology. Basal groups comprise less diverse sister groups and their distributions occur around centres of differentiation in already widespread ancestors, and not centres of origin for the whole group. Thus, the sequence of nodes in a phylogeny may indicate the spatial sequence of differentiation in a widespread ancestor rather than a series of founder dispersal events. Allocation of clades to a priori geographic areas, such as the continents, in the initial stages of biogeographic analysis has often involved incorrect assumptions of sympatry. This has led to the idea that the ‘areas of sympatry’ were centres of origin. Areas other than those defined by the taxa themselves need not be used in analysis. The fossil-calibrated molecular clock, with dates transmogrified from minimum to maximum dates, has been used to test for vicariance. Recent work in population genetics, however, indicates that allopatry is caused by vicariance rather than founder dispersal, and so vicariance can instead be used to test the clock. Deriving evolutionary chronology by calibrating spatial vicariance in molecular clades with associated tectonic events is more reasonable than relying on the fossil record to give maximum (absolute) dates. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98, 757–774.

Phylogenetic biome conservatism on a global scale

How and why organisms are distributed as they are has long intrigued evolutionary biologists. The tendency for species to retain their ancestral ecology has been demonstrated in distributions on local and regional scales, but the extent of ecological conservatism over tens of millions of years and across continents has not been assessed. Here we show that biome stasis at speciation has outweighed biome shifts by a ratio of more than 25:1, by inferring ancestral biomes for an ecologically diverse sample of more than 11,000 plant species from around the Southern Hemisphere. Stasis was also prevalent in transocean colonizations. Availability of a suitable biome could have substantially influenced which lineages establish on more than one landmass, in addition to the influence of the rarity of the dispersal events themselves. Conversely, the taxonomic composition of biomes has probably been strongly influenced by the rarity of species' transitions between biomes. This study has implications for the future because if clades have inherently limited capacity to shift biomes, then their evolutionary potential could be strongly compromised by biome contraction as climate changes.

Intraspecific Variability and Timing in Ancestral Ecology Reconstruction: A Test Case from the Cape Flora

Thamnochortus (ca. 32 species) is an ecologically diverse genus of Restionaceae. Restionaceae comprise a major component of the southern African Cape flora, wherein eco-diversification might have been important in the generation of high levels of species richness. In an attempt to reconstruct the macroecological history of Thamnochortus, it was found that standard procedures for character state optimization make two inappropriate assumptions. The first is that ancestors are monomorphic (i.e., ecologically uniform) and the second is that eco-diversification follows, or is slower than, lineage diversification. We demonstrate a variety of coding schemes with which the assumption of monomorphy can be avoided. For unordered discrete ecological characters, presence coding and generalized frequency coding (GFC) are suboptimal because they occasionally yield illogical assignments of no state to ancestors. Polymorphism coding or use of the program DIVA are preferable in this respect but are applicable only with parsimony. For continuous eco-characters (e.g., a rainfall gradient, where individual species occur in ranges), GFC and MaxMin coding provide equally valid solutions to optimizing ranges with parsimony. However, MaxMin can be extended to likelihood approaches and is therefore preferable. With respect to rates and timing, all algorithms currently employed for ancestral ecology reconstruction bias toward slow rates of eco-diversification relative to lineage diversification. An alternative to this bias is provided by DIVA, which biases toward accelerated rates of eco-diversification and thus inferences of ecology-driven speciation. We see no way of choosing between these biases; however, phylogeneticists should be aware of them. Applying these methods to Thamnochortus, we find there to be important differences in details, yet general congruence, regarding the historical ecology of this clade. We infer the most recent common ancestor of Thamnochortus to have been a post-fire resprouting species distributed on rocky, well-drained, sandstone-derived soils at lower-middle elevations, in regions of moderate levels of yearly (primarily winter) rainfall. This species would have been distributed in habitats much like those of the southwestern Cape mountains today. Major ecological trends include shifts to lower rainfall regimes and shifts from sandstone to limestone-derived alkaline soils at lower altitudes.

The Ancestral Ecology of Angiosperms: Emerging Perspectives from Extant Basal Lineages

The early ecophysiological trajectories of angiosperm evolution remain uncertain. This hinders resolution of the possible ecological and physiological catalysts that set the stage for the emergence of our modern flora. One approach for generating hypotheses on the early ecology of angiosperms is to consider the distribution of functional traits among lineages that diverge near the root of the extant angiosperm phylogenetic tree. Using recent phylogenetic results to choose lineages for comparative work, we review and expand on previous studies that examine the ecology and physiology of basal angiosperm lineages. Phylogenetic mapping of functional traits reveals that the basal lineages, Amborella, Austrobaileyales, and some Chloranthaceae, share ecological and physiological traits linked to shady, disturbed, and possibly wet habitats. Traits include low and easily light‐saturated photosynthetic rates, absence of leaf palisade cells, guttation resulting from root pressure, as well as small seed sizes. Some C...

Phylogeny, historical ecology and systematics of some mushroom-associated mites of the genus Sancassania (Acari : Acaridae),with new generic synonymies

Parsimony analysis of morphological data reveals that several species of acarid mites previously assigned to the genera Rhizoglyphus Claparède, Rhizoglyphoides Volgin and Mycetosancassania Klimov, and some undescribed species, represent a monophyletic group within the genus Sancassania Oudemans. The genera Rhizoglyphoides and Mycetosancassania syn. nov. are considered as junior synonyms of the genus Sancassania. Four new combinations are proposed: Sancassania rotundata (Nesbitt, 1944), comb. nov. (from Rhizoglyphus); Sancassania germanica (Berlese, 1921), comb. nov. (from Rhizoglyphus); Sancassania nidicola (Volgin, 1978), comb. nov. (from Rhizoglyphoides); and Sancassania grifolapholiotae (Klimov, 2000), comb. nov. (from Mycetosancassania). Sancassania nidicola and S. germanica are redescribed from type specimens, S. rotundata is redescribed from material from the USA (Michigan). Three new species are described: S. nesbitti, sp. nov., S.���ojibwa, sp. nov. (North America) and S. mironovi, sp. nov. (Northern Asia). This lineage, nidicola(grifolapholiotae(nesbitti, sp. nov. (germanica + mironovi, sp. nov.) (ojibwa, sp. nov. + rotundata))), probably originated in the Palaearctic region from relatively derived Sancassania with short supracoxal setae. The ancestor was probably polyphagous, dispersing on a variety of hosts. We hypothesise that S. nidicola, the most primitive species of the clade, may retain the ancestral ecology. The other members of the clade have specialised to feed on mushrooms and adapted their phenology to exploit this short-lived resource.

The evolution of pulse crops

From a consideration of evolution under domestication in the pulses a common pattern emerges. It is suggested that positive selection for a single character, namely, seed size, could have set in motion a complex of selection pressures that not only produced larger seeds and fruits but concomitantly produced a modified shoot architecture. The ultimate production of dwarf plants capable of free-standing growth effectively liberated pulses from dependence on other species for mechanical support and from the implications of their ancestral ecology. Characteristic features of individual pulse species not found in their closest wild relatives can almost invariably be found in other members of the same tribe or elsewhere in the family. This suggests a deep underlying genetical homology in the family as a whole and that Vavilov’s law of homologous series could with benefit be extended beyond the cultigens and enable plant breeders to set themselves more ambitious yet realistic objectives. It appears that pulses have evolved not by producing novel characters under domestication, but rather novel combinations of characters already expressed in wild forms.