Mainland Species Research Articles

The Current High Bird Colonisation Rate in a Major Mediterranean Island is Consistent With a More Intense Past Defaunation Compared to Nearby Mainland

ABSTRACTAimWe expand here previous own biogeographic work on the determinants of avian colonisation of a major land‐bridge Mediterranean island. So far we have explained mechanistically the high current rate of colonisation of the island which proceeds by overflow of mainland species with growing population trends and with prior experience as winter visitors. However, here we focus on the historical factors that have led to such a high colonisation rate.LocationMajorca Island and a nearby Iberian mainland coastal region with equivalent characteristics (Alicante province).Time PeriodTwenty‐five years (1991–2015).Major Taxa StudiedBirds.MethodsWe compared the pattern of species gain and loss in Majorca and Alicante during the study period.ResultsWe found that while Alicante only gained eight new species and lost one, Majorca lost none and gained 21 species as breeders (odds ratio 2.6). The process of species gains in 5‐year periods since 1991 showed a nonlinear pattern in both regions, with an abrupt decline in Alicante starting in 2006–2010 and final stagnation during 2011–2015, but just a smooth and recent pattern of slowdown in Majorca (2011–2015 on). Taxonomic diversity of colonising species at the family level, as well as habitat of colonisation, were quite similar between regions, but larger body size species were more common in Majorca.Main ConclusionsWe conclude that current differential colonisation rates between both regions are consistent with a more intense past defaunation of the resource‐poor region (Majorca) prior to modern rural flight that happened simultaneously in both regions. While Alicante could be approaching a theoretical carrying capacity in the number of species, Majorca is farther from it. We predict that the island will continue gaining species in the next few decades. Worldwide, further research on comparing wildlife recovery rates between regions with differential intensity of past wildlife defaunation is badly needed to understand biodiversity recovery processes.

Rectifying a century of misidentifications: a taxonomic re-evaluation of sipo snakes (Colubridae: Chironius) on Trinidad

The island of Trinidad has several endemic reptile species that in some cases are morphologically indistinguishable, or almost so, from their mainland counterparts. In particular, many snakes from the island have not been examined thoroughly with modern scientific methods and may therefore be misidentified. At least two species of sipo snakes (Chironius carinatus, C. septentrionalis) are reported to inhabit Trinidad, both being considered species already inhabiting the mainland, though their identities are based solely on morphology. Here, we evaluate the molecular distinctiveness of these Trinidadian snakes and assess their relationships to other members of the genus. We constructed a multi-locus data set (12S rRNA, 16S rRNA, cyt b, ND4, cmos, NT3, Rag-1, Rag-2) including novel sequences and those available on GenBank to perform Bayesian and maximum likelihood phylogenetic analyses. Our phylogenetic reconstruction elucidates the identity of both Trinidad species, which have been misidentified since their discovery, and we provide a literature review of their taxonomic history. More specifically, our results suggest that the Trinidad population of Chironius carinatus is an undescribed species, that we describe herein as Chironius nigelnoriegai sp. nov., and is the sister to C. flavopictus. Our results also demonstrate that the Trinidad population previously identified as C. septentrionalis is instead the mainland species C. cochranae, a member of a clade with C. foveatus, C. laurenti, and C. multiventris. Finally, we generated a time tree and inferred that our new species separated from C. flavopictus approximately 4 million years ago in the Pliocene, a time when the island of Trinidad detached from Northern Venezuela. This work contributes to a better understanding of species diversity of Trinidad and we hope that it assists in conservation efforts towards this important endemic region. These findings support the prospect of rapid speciation on Trinidad and implies that more extensive surveys of island squamates will reveal additional cryptic diversity. http://zoobank.org/urn:lsid:zoobank.org:pub:500DB91B-62CD-4051-9831-0BEEAC64C8E2

Genomic evolution of island birds from the view of the Swinhoe's pheasant (Lophura swinhoii).

Island endemic birds account for the majority of extinct vertebrates in the past few centuries. To date, the evolutionary characteristics of island endemic bird's is poorly known. In this research, we de novo assembled a high-quality chromosome-level reference genome for the Swinhoe's pheasant, which is a typical endemic island bird. Results of collinearity tests suggest rapid ancient chromosome rearrangement that may have contributed to the initial species radiation within Phasianidae, and a role for the insertions of CR1 transposable elements in rearranging chromosomes in Phasianidae. During the evolution of the Swinhoe's pheasant, natural selection positively selected genes involved in fecundity and body size functions, at both the species and population levels, which reflect genetic variation associated with island adaptation. We further tested for variation in population genomic traits between the Swinhoe's pheasant and its phylogenetically closely related mainland relative the silver pheasant, and found higher levels of genetic drift and inbreeding in the Swinhoe's pheasant genome. Divergent demographic histories of insular and mainland bird species during the last glacial period may reflect the differing impact of insular and continental climates on the evolution of species. Our research interprets the natural history and population genetic characteristics of the insular endemic bird the Swinhoe's pheasant, at a genome-wide scale, provides a broader perspective on insular speciation, and adaptive evolution and contributes to the genetic conservation of island endemic birds.

A high-quality genome for the slender anole (Anolis apletophallus): an emerging model for field studies of tropical ecology and evolution.

The slender anole, Anolis apletophallus, is a small arboreal lizard of the rainforest understory of central and eastern Panama. This species has been the subject of numerous ecological and evolutionary studies over the past 60 years as a result of attributes that make it especially amenable to field and laboratory science. Slender anoles are highly abundant, short-lived (nearly 100% annual turnover), easy to manipulate in both the lab and field, and are ubiquitous in the forests surrounding the Smithsonian Tropical Research Institute in Panama, where researchers have access to high-quality laboratory facilities. Here, we present a high-quality genome for the slender anole, which is an important new resource for studying this model species. We assembled and annotated the slender anole genome by combining 3 technologies: Oxford Nanopore, 10× Genomics Linked-Reads, and Dovetail Omni-C. We compared this genome with the recently published brown anole (Anolis sagrei) and the canonical green anole (Anolis carolinensis) genomes. Our genome is the first assembled for an Anolis lizard from mainland Central or South America, the regions that host the majority of diversity in the genus. This new reference genome is one of the most complete genomes of any anole assembled to date and should facilitate deeper studies of slender anole evolution, as well as broader scale comparative genomic studies of both mainland and island species. In turn, such studies will further our understanding of the well-known adaptive radiation of Anolis lizards.

Different patterns of introgression in a three species hybrid zone among European cave salamanders.

Hybrid zones occur where genetically distinct populations meet, mate and produce offspring with mixed ancestry. In Plethodontid salamanders, introgressive hybridization is a common phenomenon, where hybrids backcross with parental populations leading to the spread of new alleles into the parental genomes. Whereas many hybrid zones have been reported in American Plethodontid salamanders, only a single hybrid zone has been documented in European plethodontids so far, which is located at the Apuan Alps in the Italian Peninsula. Here, we describe a previously unreported hybrid zone in the Northern Apennines involving all the three Plethodontid salamander species inhabiting the Italian Peninsula. We found 21 new Speleomantes sites of occurrence, from a hitherto unexplored area located at the boundaries between three Speleomantes species ranges. Using mitochondrial (Cytb and ND2 genes) and nuclear markers (two diagnostic SNPs at the NCX1 gene), we revealed a three-way contact zone where all the three mainland species hybridize: S. strinatii, S. ambrosii and S. italicus. We observed a strong mitonuclear discordance, with mitochondrial markers showing a conspicuous geographic pattern, while diagnostic nuclear SNPs coexisted in both the same populations and individuals, providing evidence of hybridization in many possible combinations. The introgression is asymmetric, with S. italicus mitogenome usually associated with S. a. ambrosii and, to a lesser extent, to S. strinatii nuclear alleles. This finding confirms that Plethodontid are a group of choice to investigate hybridization mechanisms and suggests that behavioural, genetic and ecological components may concur in determining the direction and extent of introgression.

The extirpation of medium and large mammal species from the Ehotilé Islands National Park, south-eastern Côte d’Ivoire

Abstract In West Africa, high deforestation rates and poaching have induced dramatic declines of mammal’s populations and local extinctions. Due to their isolation, island species are more vulnerable than mainland species. The premises of that scenario are perceptible in the Ehotilé Islands National Park, south-eastern Côte d’Ivoire, but have not been documented. This study aimed to update the diversity and conservation status of medium and large mammals in that protected area. Several surveys were conducted between 2019 and 2021, using ethno-zoological interviews and individual surveys with local populations, as well as reconnaissance walks and camera trapping to collect data on the presence or absence of mammals. From interviews with local populations and literature review, a list of 27 species of mammals that were potentially present in the park in the past was established. Most “lost” species are large mammals, especially primates that are globally threatened. A total of 11 species were pictorially identified, including two Near threatened species (Aonyx capensis and Hydrictis maculicollis) and one Vulnerable species (Cercopithecus lowei). The study confirms a trend of population decline and the erosion of mammal diversity in the park, hence highlighting the need for urgent conservation actions.

Revision of Microasydates, New Nearctic Genus of Soft-Winged Flower Beetles (Coleoptera: Melyridae: Dasytinae: Listrini)

A group of four North American dasytine species is carved from the genus Trichochrous Motschulsky, 1860. The genus Microasydates Gimmel and Mayor, new genus (type species: Pristoscelis umbratus LeConte, 1866) is created for these species. This new genus is clearly defined based on several adult male characters, including the presence of a field of coarse black setae concentrated medially on abdominal ventrite 4, slender tibial spurs in combination with the head not distinctly enlarged, lack of a basal strut on abdominal sternite VIII, tegmen membranous apically, and ventral teeth on the median lobe of the aedeagus. Species are distinguished primarily by characters of pronotal shape, setation, female pygidium, and the median lobe of the male aedeagus. Previously described are Microasydates punctipennis (LeConte, 1866), new combination and Microasydates umbratus (LeConte, 1866), new combination. Newly described are Microasydates sanclemente Gimmel and Mayor, new species and Microasydates santabarbara Gimmel and Mayor, new species. The only widespread mainland species is M. umbratus, which occurs almost throughout California across the Great Basin into Utah, while the remainder of the diversity is in the California Channel Islands and Santa Ynez Mountains in Santa Barbara County. Upon examination of type material, Trichochrous indigens Casey, 1895, Trichochrous nubilatus Casey, 1895, Trichochrous separatus Casey, 1895, Trichochrous suffusus Casey, 1895, Trichochrous testaceus Casey, 1895, and Trichochrous pratensis Blaisdell, 1924 are all considered new junior subjective synonyms of M. umbratus. Trichochrous fulvovestitus Casey, 1895, status restored, and its junior synonym, Trichochrous propinquus Casey, 1895, are removed from synonymy with M. umbratus and retained in the genus Trichochrous. Adults of Microasydates are active during mid to late summer, and aggregate, often in large numbers, on the flowers of a wide variety of mostly perennial plants, where they mate and apparently feed on pollen, nectar, and occasionally small arthropods. Seasonality data and known host plant associations are provided along with species treatments.

The ‘island syndrome’ is an alternative state

AbstractAimIn the half‐century since publication of the Theory of Island Biology, ecologists have come to recognize the importance of predation as a decisive determinant of alternate states in many ecosystems. Island species are notorious for their vulnerability to introduced predators, yet the strength of island predator regimes has not been fully incorporated into our understanding of the forces that structure island consumer communities.LocationThe Greater and Lesser Antilles.TaxonBirds andAnolislizards.MethodsField surveys of sclerophyll and rainforest sites on islands ranging in size from 3.5 km2Terre‐de‐Haut to 76,000 km2Hispaniola.ResultsEvidence gathered in the 1970s and 1980s shows that Antillean anoles live at higher densities on fewer resources, grow more slowly, reproduce later and live longer than mainland counterparts in conformity with the ‘island syndrome’. Data from this period show that Antillean bird communities display density overcompensation, community saturation, size‐structured foraging guilds, low species diversity and low species packing, all traits consistent with the island syndrome and a regime of low predation and intense competition. Mainland species and communities display none of these features.Main conclusionsI propose that the island syndrome is an alternative state that distinguishes low‐predation island communities from high‐predation mainland counterparts. It follows that strong mainland predation regimes tend to prevent island species from colonizing. Conversely, invasion‐resistant, size‐structured island communities, despite low species diversity, prevent mainland species from colonizing islands. These predictions are experimentally testable withAnolislizards and, if confirmed, could set island biogeography on a new course.

The Phylogenetic Limits to Diversity-Dependent Diversification.

While the theory of micro-evolution by natural selection assigns a crucial role to competition, its role in macroevolution is less clear. Phylogenetic evidence for a decelerating accumulation of lineages suggests a feedback of lineage diversity on diversification. However, does this feedback only occur between close relatives, or do distant relatives also influence each other's diversification? In other words: are there phylogenetic limits to this diversity-dependence? Islands form ideal systems to answer these questions because their boundedness facilitates an overview of all potential competitors. The DAISIE (Dynamic Assembly of Island biota through Speciation Immigration and Extinction) framework allows for testing the presence of diversity-dependence on islands given phylogenetic data on colonization and branching times. The current inference models in DAISIE assume that this diversity-dependence only applies within a colonizing clade, i.e., all mainland species can colonize and diversify independently from one another. We term this clade-specific (CS) diversity-dependence. Here we introduce a new DAISIE model that assumes that diversity-dependence applies to all island species of a taxonomic group regardless of their mainland ancestry, i.e., diversity-dependence applies both to species within the same clade and between different clades established by different mainland species. We call this island-wide (IW) diversity-dependence. We present a method to compute a likelihood for this model given phylogenetic data on colonization and branching events and use likelihood ratio bootstrapping to compare it to the likelihood of the CS model in order to overcome biases known for standard model selection. We apply it to the diversification of Eleutherodactylus frogs on Hispaniola. Across the Greater Antilles archipelago, this radiation shows repeated patterns of diversification in ecotypes that are similar across clades. This could be suggestive of overlapping niche space and hence between-clade interactions, i.e., IW diversity-dependence. But it could also be suggestive of only within-clade interactions because between-clade interactions would have blocked the same ecotype from re-appearing. We find that the CS model fits the data much better than the IW model, indicating that different colonizations while resulting in similar ecotypes, are sufficiently distinct to avoid interacting strongly. We argue that non-overlapping distributions between clades (both spatially and in terms of ecotypes) cannot be used as evidence of CS diversity-dependence, because this pattern may be a consequence of IW diversity-dependence. By contrast, by using phylogenetic data rather than distributional data our method does allow for inferring the phylogenetic limits to diversity-dependent diversification. We discuss possibilities for future extensions and applications of our modelling approach. [Adaptive radiation; birth-death model; Caribbean; diversity-dependence; Eleutherodactylus; island biogeography.].

The fossil record of turtles from the Pleistocene of Crete (Greece)

The Isle of Crete contains an important endemic fossil fauna that has been studied extensively in the past. An endemic fossil tortoise, Testudo marginata cretensis Bachmayer, Brinkerink & Symeonidis, 1975, had previously been named from Pleistocene cave deposits in the island, presumably being larger than the mainland species and having some important morphological differences as well. In this paper I revise these type specimens and describe for the first time numerous additional fossil specimens from the Pleistocene sites of Gerani IV, Zourida, Koumpes, Liko, Mavro Mouri IV, and Simonelli Caves (near Herakleion), Rethymnon fissure, and from the open site of Sitia in the eastern part of the Island. These specimens belong mostly to the marginated tortoise, but the presence of a terrapin is confirmed as well. These new fossils help to refute the validity of the Cretan subspecies, and change the range of the marginated tortoise during Pleistocene/Holocene times in the southern Balkans.

Genetic structure and geneflow of Malus across the Korean Peninsula using genotyping-by-sequencing

This study was to understand the genetic structure and diversity of the Korean Malus species. We used genotyping-by-sequencing (GBS) technology to analyze samples of 112 individuals belonging to 18 populations of wild Malus spp. Using GBS, we identified thousands of single nucleotide polymorphisms in the species analyzed. M. baccata and M. toringo, two dominant mainland species of the Korean Peninsula, were distinguishable based on their genetic structure. However, M. toringo collected from Jeju Island exhibited a different genetic profile than that from the mainland. We identified M. cf. micromalus as a hybrid resulting from the Jeju Island M. toringo (pollen donor) and the mainland M. baccata, (pollen recipient). Putative M. mandshurica distributed on the Korean Peninsula showed a high structural and genetic similarity with M. baccata, indicating that it might be an ecotype. Overall, this study contributes to the understanding of the population history and genetic structure of Malus in the Korean Peninsula.

Two new records of insects (Arthropod: Insecta) from Dokdo Islands, Korea

Dokdo, a group of oceanic islands located in the East Sea near Ulleungdo Island, Korea, has great biological and ecological diversity. The ecosystem of Dokdo is considered unique because the oceanic climate differs from that of mainland Korea, and the islands have remained isolated for an extended period due to their geographic features. Biological surveys of insects were conducted five times on Dongdo and twice on Seodo in 2019 and 2020. From these surveys, we could find a total of ten orders, 82 families, and 190 species of insects, including two newly described species: Geocoris ( Geocoris ) pallidipennis (Costa) (Hemiptera: Lygaeidae) and Tephrochlamys japonica (Okadome) (Diptera: Heleomyzidae). These survey results suggest that Dokdo is very important from both academic and conservation perspectives. Establishing a complete database of Dokdo insects will require continued investigations. Such a database would provide basic information for inferring correlations with mainland species.

Discovering endemic species among the bumblebees of Taiwan (Apidae, genus Bombus)

ABSTRACT It is well established that there are nine species of bumblebees indigenous to Taiwan, but what has been unclear is how many of them are endemic. We examine minimum divergence in COI barcodes and morphology between Taiwanese samples and some of the nearest mainland populations and compare the results with more detailed global coalescent analyses available for some of these species. Our results support separate status for four of the species, including the two species inferred to be endemic from coalescent and morphological evidence. We support the other five species as conspecific with mainland species, four of which are also inferred to be conspecific from coalescent and morphological evidence. This conclusion requires the description of one new endemic species, Bombus taiwanensis sp. nov., which can be diagnosed by integrated evidence from its COI (cytochrome c oxidase subunit I) barcodes, its colour pattern and its morphology.

Revision of the genus Adiscus Gistel, 1857 (Coleoptera: Chrysomelidae, Cryptocephalinae) from mainland China.

The mainland Chinese fauna of the leaf beetle genus Adiscus Gistel, 1857 is revised and three new species described: Adiscus daofuensis Duan Zhou, new species from Sichuan, Gansu and Henan, A. ningshanensis Duan Zhou, new species from Shaanxi, and A. tanae Duan Zhou, new species from Tibet. One species is newly recorded from China: A. pubiventris Medvedev, 2008. The mainland Chinese fauna of Adiscus is 35 species, almost all of which are redescribed. Color illustrations and line drawings are provided and a key to all 35 Chinese mainland species. Types of the new species are deposited in the Institute of Zoology, Chinese Academy of Sciences.

Are Cenozoic relict species also climatic relicts? Insights from the macroecological evolution of the giant sedges of Carex sect. Rhynchocystis (Cyperaceae).

Most of the Paleotropical flora widely distributed in the Western Palearctic became extinct during the Mio-Pliocene as a result of global geoclimatic changes. A few elements from this Cenozoic flora are believed to remain as relicts in Macaronesia, forming part of the laurel forests. Although the origins of the present species assembly are known to be heterogeneous, it is unclear whether some species should be considered climatic relicts with conserved niches. An ideal group for studying such relict characteristics is a Miocene lineage of Carex sect. Rhynchocystis (Cyperaceae), which comprises four species distributed in mainland Palearctic and Macaronesia. We reconstructed the current and past environmental spaces for extant mainland and Macaronesian species, as well as for Pliocene fossils. We also studied the bioclimatic niche evolution. Species distribution modeling and ensemble small modeling were performed to assess the potential distribution over time. Climatic niche analyses and distribution modeling revealed that the ecological requirements of Macaronesian species did not overlap with those of either mainland species or with the Pliocene fossils. Conversely, the niches of mainland species displayed significant similarity and equivalence. Macaronesian species are not climatic relicts from the Paleotropical flora, but instead seem to have changed the ecological niche of their ancestors. By contrast, despite their ancient divergence (Late Miocene), mainland C. pendula and C. agastachys show conserved niches, with competitive exclusion likely shaping their mostly allopatric ranges.

Ecology, conservation status, and phylogenetic placement of endemic Pristimantis frogs (Anura: Craugastoridae) in Trinidad and Tobago and genetic affinities to northern Venezuela

AbstractTrinidad and Tobago are home to three endemic species in the anuran genus Pristimantis, of which two (Pristimantis charlottevillensis and Pristimantis turpinorum) occur in Tobago alone and the third (Pristimantis urichi) is present on both islands. Earlier, the IUCN assessed the conservation status of these species as: P. urichi, Endangered (EN); P. charlottevillensis, Least Concern (LC); P. turpinorum, Vulnerable (VU). However, these assessments were based on very little field‐based evidence. Here, we present survey results which contributed to reassessments as LC, VU and Data Deficient for these three species, respectively. Despite the close proximity of Trinidad to northern Venezuela, the islands do not share any Pristimantis species with the mainland, which holds a rich endemicity of Pristimantis regionally. In this study, we used genetic sequencing from several island populations and compared them to northern Venezuelan endemics to assess genetic divergence for the first time. The time tree analyses found that only the northern Tobago species P. turpinorum is closely related to mainland Pristimantis, with a genetic split dating to the Late Miocene, suggesting a vicariant event of mainland and island species. Pristimantis urichi, although identical between the two islands, remains highly divergent from the mainland species. Similar results were found for P. charlottevillensis. In addition, there was a high level of divergence between P. urichi and P. charlottevillensis. These findings indicate different island colonization events by different lineages. Sequencing other Venezuelan species remains pivotal to unravel the complexity of the colonization episodes in the region, likely influenced by the changing topography and multiple connection and isolation episodes of the islands by eustatic sea‐level changes.

Claws and toepads in mainland and island Anolis (Squamata: Dactyloidae): Different adaptive radiations with intersectional morphospatial zones.

Anolis lizards have evolved morphologies in response to different selective factors related to microhabitat use. Morphological diversity exhibits evolutionary patterns that reveal similarities and unique regional traits among the mainland and island environments and among Greater Antilles and Lesser Antilles islands. In the Greater Antilles and mainland environments anole species are classified into morphological/ecological groups, that are known as morphotypes (mainland) or ecomorphs (Greater Antilles). Morphotypes are defined only with morphological information; in contrast, for ecomorph assignment both morphology and ethology are required. For mainland species distributed in northwestern South America 10morphotypes were proposed to include the morphological diversity of 59species. We obtained data from body size, limbs length, tail length, and the number of lamellae for an additional ten species occurring in the same region and assigned them into morphotypes. We also collected data of the claw and toepad diversity of mainland and island Anolis from northwestern South America and compared it to the claw and toepads morphology recorded for the Greater Antilles and Lesser Antilles islands, under a phylogenetic framework. We found new island morphotypes (MT11-MT13) of Anolis from northwestern South America. When comparing claws and toepads morphology among the 13morphotypes we found that morphological variation of these traits partially corresponds to morphotype groups. For instance, habitat specialist species like Anolis heterodermus, classified in morphotype 4 (MT4), have a characteristic design of broad toepad and reduced claws, and non-unique design of toepads and claws occurs in morphotypes MT1, MT2, MT5, MT10, and MT13. We also compared claws and toepads of fore and hindlimbs within the same individual, and found that even if limbs show differences in claws and toepads, suggesting that they perform differential biomechanical function, the degree of within individual variation is specific and not related to morphotype assignment. Our data supported the convergent and unique regional evolution among mainland and island anoles, and revealed aspects of correlative evolution of functional traits of claws and toepads that probably are related to minor differences in microhabitat use among mainland and island species, as suggested by previously published literature. Lastly, the evolutionary pattern of morphological diversity of claws and toepads of Anolis in the mainland and island environment supports both unique regional traits and common selective and historical factors that have molded Anolis morphological diversity.

Contact calls of island Brown-throated Parakeets exhibit both character and variance shifts compared to calls of their mainland relatives

Abstract Learned vocalizations play a key role in parrot social dynamics and vocal dialects have been documented for several mainland species, but to date no studies of geographically structured call variation in parrot species have examined the role of isolation on islands. In a study of the Brown-throated Parakeet (Eupsittula pertinax), which inhabits 5 small Caribbean islands as well as the adjacent mainland, we found that the contact calls of island and mainland parakeets show divergence in vocal characters as well as in call variability. We assessed call variation using 3 approaches: frequency measurements, spectrogram cross-correlation (SPCC) analyses, and call duration measurements. Island parakeets’ calls were longer and had lower mean frequencies, and calls from different islands were distinguishable from each other as well as from mainland calls using measures derived from the SPCCs. In addition, we measured call variability at 2 different levels—within-location and within-individual. We found calls to be more variable for island parakeets for SPCC and duration measures, but less variable for frequency measures. The observed call differentiation among locations may be due to drift, whereas the lower frequency of island calls could either be a response to the windy environment on the islands or a consequence of the island subspecies’ larger body sizes. We also hypothesize that the isolation of parakeet populations on small islands may have resulted in reduced selection for local call convergence, allowing island parakeets to produce more variable calls. We suggest that due to poor signal transmission in the windy island environment, selective pressures may favor variability in more easily perceived call features (like call duration) rather than more subtle features, like frequency shifts. Experimental tests are required to determine whether observed call patterns translate into similarly structured patterns in the responses to vocal variants.

The evolutionary history of the Caribbean magnolias (Magnoliaceae): Testing species delimitations and biogeographical hypotheses using molecular data

The Caribbean islands provide an ideal setting for studying biodiversity, given their complex geological and environmental history, and their historical and current geographical proximity to the American mainland. Magnolia, a flagship tree genus that has 15 endemic and threatened taxa (12 species and 3 subspecies) on the Caribbean islands, offers an excellent case study to empirically test Caribbean biogeographical hypotheses. We constructed phylogenetic hypotheses to: (1) reveal their evolutionary history, (2) test the current largely morphology-based classification and assess species limits, and (3) investigate major biogeographic hypotheses proposed for the region. Nuclear and chloroplast DNA sequence data of all 15 Caribbean Magnolia taxa are included, supplemented by a selection of American mainland species, and species representing most major clades of the Magnoliaceae family. We constructed phylogenetic hypotheses in a time-calibrated Bayesian framework, supplemented with haplotype network analyses and ancestral range estimations. Genetic synapomorphies in the studied markers confirm the species limits of 14 out of 15 morphologically recognizable Caribbean Magnolia taxa. There is evidence for four colonization events of Magnolia into the Caribbean from the American mainland, which most likely occurred by overwater dispersal, given age estimates of maximum 16 mya for their presence on the Caribbean islands.

Evolution of song and color in island birds

Island birds are often less colorful and sing different songs than their mainland counterparts. Given that trade-offs can occur in the expression of costly sexually selected traits, it is not clear whether island species with less colorful plumage than their mainland counterparts have compensated with increased complexity of song structure. To examine potential trade-offs in sexually selected traits in island birds, we examined concurrent patterns of coloration and song structure in island and mainland (sub)species across 3 widespread and speciose songbird families: Fringillidae, Meliphagidae, and Monarchidae. Phylogenetically controlled analyses revealed a shift away from white plumage and toward melanin-based plumage in island (sub)species but only in the Meliphagidae. Contrary to our predictions, we found no evidence that song structure in island birds differed from their mainland counterparts. Although a number of inverse correlations were identified between song structure and plumage coloration when all birds were considered, this pattern became weaker when only island populations were examined. Instead, we found island size affected song structure leading to a lower number of syllables and lower minimum frequency on smaller islands. Birds on smaller islands also had reduced carotenoid plumage but this pattern was only significant in the Fringillidae. These results indicate that island environments can influence the evolution of both song and color in some taxa, but that selection is tempered by island size, rather than through correlated evolution across signaling modalities.