Example Of Adaptive Radiation Research Articles

THE THEORY OF ISLAND BIOGEOGRAPHY AT AGE 40

Review of: Losos, J. B. and R. E. Ricklefs (eds.). 2010. Theory of Island Revisited. Princeton University Press, Princeton, NJ. 476 Pages. ISBN: 978-1-4008-3192-0. $99.50 hb; $49.50 pb. Despite representing only about 3% or the earth s surface, islands have had an inordinately important impact on ecological and evolutionary thinking, beginning with the insights of Darwin and Wallace. Islands and their biotas have long fascinated biologists because of their discrete boundaries and isolation, their limited and disharmonie species richness (compared with mainland biotas), and their spectacular examples of adaptive radiation. Sewall Wright (1940) used islands as metaphors in the early days of population genetics, and island-based books written by Carlquist, Lack, and Mayr strongly influenced ecological and evolutionary in the mid-20th century. But, the seminal event that seemingly revolutionized our about evolution on and the biogeography of islands was the 1967 publication of The Theory of Island Biogeography (TTIB) by Robert H. MacArthur and Edward O. Wilson, who were both in their late 30s at the time. This 200-page monograph became an instant classic and has inspired several generations of ecologists, evolutionary biologists, and conservation biologists to add thinking to their conceptual toolkits and research and management programs. current volume is based on a 40-year retrospective on the impact of TTIB on ecology and evolution. Authors of the book's 16 chapters span several academic generations and include one of the original authors, Ed Wilson; first-generation intellectual offspring of MacArthur and Wilson (Holt, Hubbell, Ricklefs, Schoener, Simberloff, Terborgh); other older island aficionados (the Grants, Whittaker); as well as younger island researchers (Clegg, Gillespie, Hanski, Lomolino, Losos, Velland). Although TTIB had a strong impact on conservation in the 1970s and 1980s, chapters with an explicit emphasis on conservation are missing from this book (conservation has no entry in the index), whose primary focus, as in the original monograph, is on ecology and evolution. This is unfortunate because some of the world's most pressing current conservation concerns come from islands where many plants and animals have suffered accelerated extinction rates via the hand of man.

Darwin's Galápagos finches in modern biology

One of the classic examples of adaptive radiation under natural selection is the evolution of 15 closely related species of Darwin's finches (Passeriformes), whose primary diversity lies in the size and shape of their beaks. Since Charles Darwin and other members of the Beagle expedition collected these birds on the Galápagos Islands in 1835 and introduced them to science, they have been the subjects of intense research. Many biology textbooks use Darwin's finches to illustrate a variety of topics of evolutionary theory, such as speciation, natural selection and niche partitioning. Today, as this Theme Issue illustrates, Darwin's finches continue to be a very valuable source of biological discovery. Certain advantages of studying this group allow further breakthroughs in our understanding of changes in recent island biodiversity, mechanisms of speciation and hybridization, evolution of cognitive behaviours, principles of beak/jaw biomechanics as well as the underlying developmental genetic mechanisms in generating morphological diversity. Our objective was to bring together some of the key workers in the field of ecology and evolutionary biology who study Darwin's finches or whose studies were inspired by research on Darwin's finches. Insights provided by papers collected in this Theme Issue will be of interest to a wide audience.

Breeding Ecology of the Tylas VangaTylas eduardiin Southeastern Madagascar

Abstract Although the family Vangidae provides one of the most striking examples of adaptive radiation in the avifauna of Madagascar, basic information on the breeding biology of each species is lacking. To examine the breeding system of the Tylas Vanga Tylas eduardi, a species endemic to Madagascar, we studied the contributions made by males and females of two pairs (involving four nests) to nest building, incubating, brooding, and feeding the young. The study was conducted from October 2007 to January 2008 at Ranomafana National Park, situated in southeastern Madagascar. Males had dispersed territories and paired with single females. Copulation took place between females and males on whose territories they nested. During the nest-building stage, males and females provided nest materials. We observed parental care at two nests. Both sexes participated in incubating and brooding at one nest, whereas only the female incubated and brooded at another nest. During the nestling period, both sexes delivered foo...

Cooperative Breeding in the Endemic Madagascan Chabert's VangaLeptopterus chabert

The family Vangidae provides one of the most striking examples of adaptive radiation in the Madagascan avifauna, nevertheless, basic information on the breeding biology of many species remains lacking. To examine the breeding system of the endemic Madagascan Chabert's Vanga Leptopterus chabert, we studied the contributions made by adults to nest building, incubating, brooding, and feeding the young at six nests. The study was conducted during November and December in 1999, 2000, and 2005 at Ankarafantsika Strict Nature Reserve. During the nest-building stage, two adults (perhaps a heterosexual pair) delivered nest materials. Two adults participated in incubating and brooding. During the nestling period, several (3–4) adults delivered food (mainly bees, dragonflies, and moths) to the nestlings at two nests. They also mobbed animals that approached the nest. During the post-fledging period, several (3–4) adults fed the fledglings in two family groups. These observations suggest that Chabert's Vangas are cooperative breeders in which several adults feed the young of one brood.

Living together but remaining apart: comparative phylogeography of Anolis poncensis and A. cooki, two lizards endemic to the aridlands of Puerto Rico

Comparative phylogeography is a powerful method for testing hypotheses of evolutionary diversification in ecological communities. Caribbean lizards of the genus Anolis are a species-rich group and a well-known example of adaptive radiation. In 1983, Ernest Williams suggested that species of Anolis that belong to the same ‘climate type’ (taxa that occur sympatrically in either xeric, mesic or very wet habitats) probably evolved under similar ecological conditions, and thus have experienced a parallel evolutionary history. This hypothesis implies that the phylogeographical patterns of such species can be expected to be concordant, a prediction that has not been tested. We conducted a comparative phylogeographical and population genetic study of Anolis poncensis and Anolis cooki, two sympatric lizards restricted to the aridlands of southwestern Puerto Rico, to determine whether there are similarities in the genetic architecture of the two anoles that may have resulted from a parallel response to the same historical events, or whether each taxon displays a distinct pattern of geographical distribution of intraspecific genealogical lineages. Our dataset consisted of approximately 2120 base pairs of the ND2 and cytochrome b genes from specimens from the known extant populations of the two species. The average haplotype diversity in A. poncensis (0.36) was considerably lower than that in A. cooki (0.62), whereas the average nucleotide diversity in A. cooki was ten times higher than that in A. poncensis. Both anoles showed pronounced phylogeographical structure, with no shared haplotypes among populations. The gene genealogy of A. poncensis recovered three strongly supported clades: the westernmost population, the easternmost deme and the three intermediate populations. In A. cooki, the populations from the western part of the species' range formed a well-supported group, to the exclusion of the eastern demes. Pairwise FST values revealed significant genetic differentiation among all conspecific populations of both anoles. Coalescent simulations indicated that A. poncensis could have evolved under a scenario of simple population fragmentation during the Pleistocene, but that A. cooki did not. The estimate of the effective population size of A. cooki was an order of magnitude larger than that of A. poncensis. Because time to the most recent common ancestor is dependent on effective population size, this tenfold difference implies that the time to the most recent common ancestor of A. cooki is much longer than that of A. poncensis, which indicates that A. cooki diversified earlier than A. poncensis. Collectively, these findings suggest that, although A. poncensis and A. cooki are syntopic throughout much of their current distribution, intraspecific diversification in the two species has not proceeded in parallel, which does not support the hypothesis that Anolis lizards that occupy the same climate-type region possess spatially and temporally congruent genetic architectures. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 96, 617–634.

The interaction of sexually and naturally selected traits in the adaptive radiations of cichlid fishes

The question of how genetic variation translates into organismal diversity has puzzled biologists for decades. Despite recent advances in evolutionary and developmental genetics, the mechanisms that underlie adaptation, diversification and evolutionary innovation remain largely unknown. The exceptionally diverse species flocks of cichlid fishes are textbook examples of adaptive radiation and explosive speciation and emerge as powerful model systems to study the genetic basis of animal diversification. East Africa's hundreds of endemic cichlid species are akin to a natural mutagenesis screen and differ greatly not only in ecologically relevant (hence naturally selected) characters such as mouth morphology and body shape, but also in sexually selected traits such as coloration. One of the most fascinating aspects of cichlid evolution is the frequent occurrence of evolutionary parallelisms, which has led to the question whether selection alone is sufficient to produce these parallel morphologies, or whether a developmental or genetic bias has influenced the direction of diversification. Here, I review fitness-relevant traits that could be responsible for the cichlids' evolutionary success and assess whether these were shaped by sexual or natural selection. I then focus on the interaction and the relative importance of sexual vs. natural selection in cichlid evolution. Finally, I discuss what is currently known about the genes underlying the morphogenesis of adaptively relevant traits and highlight the importance of the forthcoming cichlid genomes in the quest of the genetic basis of diversification in this group.

Introduced Avian Diseases, Climate Change, and the Future of Hawaiian Honeycreepers

The Hawaiian archipelago is isolated in the central Pacific and consists of 7 large islands and a chain of low coral atolls and small rocky islets that extend in a long arc from Hawaii Island in the southeast to Kure Atoll in the northwest. The archipelago is the most isolated island system in the world, separated from the nearest continental landmass by more than 2000 miles of ocean.1 The islands range in elevation from just above sea level for atolls in the Northwestern Hawaiian Islands to peaks that exceed 4000 m on Hawaii Island. The interaction of extreme topographic relief, trade winds, and local climatic patterns creates a wide diversity of habitats, ranging from alpine deserts on the highest peaks to montane rain forests with precipitation exceeding 7600 mm per year. The endemic passerine avifauna of the Hawaiian Islands, particularly the endemic Hawaiian hon eycreepers (subfamily Drepanidinae) is often heralded as an outstanding example of adaptive radiation, equal to Darwin's finches from the Galapagos Islands in terms of diversity of bill types and number of species that descended from a common founder.2 From an initial colonization by only a few individuals of a single ancestral cardueline finch, this group radiated throughout the diverse habitats on the islands, specializing on a variety of food resources that included nectar, fruits, and insects. Based on recent studies of subfossils, the diversity of this group may have reached 20 genera with more than 50 species prior to human contact with the islands.3 Remarkably, a new genus and species of honeycreeper, the po'ouli {Melamprosops phaeosoma), was described in the 1970s from remote rain forests on Maui.4 Today, the endemic Hawaiian avifauna faces one of the highest rates of extinction in the world.

Convergent evolution of ‘creepers’ in the Hawaiian honeycreeper radiation

Natural selection plays a fundamental role in the ecological theory of adaptive radiation. A prediction of this theory is the convergent evolution of traits in lineages experiencing similar environments. The Hawaiian honeycreepers are a spectacular example of adaptive radiation and may demonstrate convergence, but uncertainty about phylogenetic relationships within the group has made it difficult to assess such evolutionary patterns. We examine the phylogenetic relationships of the Hawaii creeper (Oreomystis mana), a bird that in a suite of morphological, ecological and behavioural traits closely resembles the Kauai creeper (Oreomystis bairdi), but whose mitochondrial DNA (mtDNA) and osteology suggest a relationship with the amakihis (Hemignathus in part) and akepas (Loxops). We analysed nuclear DNA sequence data from 11 relevant honeycreeper taxa and one outgroup to test whether the character contradiction results from historical hybridization and mtDNA introgression, or convergent evolution. We found no evidence of past hybridization, a phenomenon that remains undocumented in Hawaiian honeycreepers, and confirmed mtDNA and osteological evidence that the Hawaii creeper is most closely related to the amakihis and akepas. Thus, the morphological, ecological and behavioural similarities between the evolutionarily distant Hawaii and Kauai creepers represent an extreme example of convergent evolution and demonstrate how natural selection can lead to repeatable evolutionary outcomes.

Biogeography of the fauna of French Polynesia: diversification within and between a series of hot spot archipelagos

The islands of French Polynesia cover an area the size of Europe, though total land area is smaller than Rhode Island. Each hot spot archipelago (Societies, Marquesas, Australs) is chronologically arranged. With the advent of molecular techniques, relatively precise estimations of timing and source of colonization have become feasible. We compile data for the region, first examining colonization (some lineages dispersed from the west, others from the east). Within archipelagos, blackflies (Simulium) provide the best example of adaptive radiation in the Societies, though a similar radiation occurs in weevils (Rhyncogonus). Both lineages indicate that Tahiti hosts the highest diversity. The more remote Marquesas show clear examples of adaptive radiation in birds, arthropods and snails. The Austral Islands, though generally depauperate, host astonishing diversity on the single island of Rapa, while lineages on other islands are generally widespread but with large genetic distances between islands. More recent human colonization has changed the face of Polynesian biogeography. Molecular markers highlight the rapidity of Polynesian human (plus commensal) migrations and the importance of admixture from other populations during the period of prehistoric human voyages. However, recent increase in traffic has brought many new, invasive species to the region, with the future of the indigenous biota uncertain.

Testing the island effect in adaptive radiation: rates and patterns of morphological diversification in Caribbean and mainlandAnolislizards

Many of the classic examples of adaptive radiation, including Caribbean Anolis lizards, are found on islands. However, Anolis also exhibits substantial species richness and ecomorphological disparity on mainland Central and South America. We compared patterns and rates of morphological evolution to investigate whether, in fact, island Anolis are exceptionally diverse relative to their mainland counterparts. Quite the contrary, we found that rates and extent of diversification were comparable--Anolis adaptive radiation is not an island phenomenon. However, mainland and Caribbean anoles occupy different parts of morphological space; in independent colonizations of both island and mainland habitats, island anoles have evolved shorter limbs and better-developed toe pads. These patterns suggest that the two areas are on different evolutionary trajectories. The ecological causes of these differences are unknown, but may relate to differences in predation or competition among mainland and island communities.

Annotation of expressed sequence tags for the East African cichlid fish Astatotilapia burtoni and evolutionary analyses of cichlid ORFs

BackgroundThe cichlid fishes in general, and the exceptionally diverse East African haplochromine cichlids in particular, are famous examples of adaptive radiation and explosive speciation. Here we report the collection and annotation of more than 12,000 expressed sequence tags (ESTs) generated from three different cDNA libraries obtained from the East African haplochromine cichlid species Astatotilapia burtoni and Metriaclima zebra.ResultsWe first annotated more than 12,000 newly generated cichlid ESTs using the Gene Ontology classification system. For evolutionary analyses, we combined these ESTs with all available sequence data for haplochromine cichlids, which resulted in a total of more than 45,000 ESTs. The ESTs represent a broad range of molecular functions and biological processes. We compared the haplochromine ESTs to sequence data from those available for other fish model systems such as pufferfish (Takifugu rubripes and Tetraodon nigroviridis), trout, and zebrafish. We characterized genes that show a faster or slower rate of base substitutions in haplochromine cichlids compared to other fish species, as this is indicative of a relaxed or reinforced selection regime. Four of these genes showed the signature of positive selection as revealed by calculating Ka/Ks ratios.ConclusionAbout 22% of the surveyed ESTs were found to have cichlid specific rate differences suggesting that these genes might play a role in lineage specific characteristics of cichlids. We also conclude that the four genes with a Ka/Ks ratio greater than one appear as good candidate genes for further work on the genetic basis of evolutionary success of haplochromine cichlid fishes.

Editorial and Retrospective 2008

Editorial and Retrospective 2008

MHC, TSP, and the Origin of Species: From Immunogenetics to Evolutionary Genetics

The acronym Mhc, major histocompatibility complex, is customarily not allied with topics in evolutionary biology. Here, however, we attempt to demonstrate that the Mhc has much to offer to this discipline and intimate that evolutionary biologists who ignore its contributions miss out on a chance of applying a new approach to vexing questions. One aspect of the Mhc in particular affords a fresh look at the population processes that transform one species into another: the trans-species polymorphism, the passage of allelic lineages from ancestral to descendant species. We provide examples of using the Mhc polymorphism in estimating the size of the founding population of new species, and of analyzing the long-term population demographies of phylogenetic lineages. We then extend the concept of trans-species polymorphism to other genes, even those not evolving under balancing selection, and argue that the phenomenon is widespread between closely related species. On the example of the cichlid fishes of Lake Victoria, we demonstrate how the concept changes the interpretation of this so-called "species flock." We contend that the conclusions reached regarding the cichlid fishes apply also to other examples of adaptive radiation, for example that of Darwin's finches, and so provide new insights into the nature of speciation in general.

GEOMETRIC MORPHOMETRIC ANALYSES PROVIDE EVIDENCE FOR THE ADAPTIVE CHARACTER OF THE TANGANYIKAN CICHLID FISH RADIATIONS

The cichlids of East Africa are renowned as one of the most spectacular examples of adaptive radiation. They provide a unique opportunity to investigate the relationships between ecology, morphological diversity, and phylogeny in producing such remarkable diversity. Nevertheless, the parameters of the adaptive radiations of these fish have not been satisfactorily quantified yet. Lake Tanganyika possesses all of the major lineages of East African cichlid fish, so by using geometric morphometrics and comparative analyses of ecology and morphology, in an explicitly phylogenetic context, we quantify the role of ecology in driving adaptive speciation. We used geometric morphometric methods to describe the body shape of over 1000 specimens of East African cichlid fish, with a focus on the Lake Tanganyika species assemblage, which is composed of more than 200 endemic species. The main differences in shape concern the length of the whole body and the relative sizes of the head and caudal peduncle. We investigated the influence of phylogeny on similarity of shape using both distance-based and variance partitioning methods, finding that phylogenetic inertia exerts little influence on overall body shape. Therefore, we quantified the relative effect of major ecological traits on shape using phylogenetic generalized least squares and disparity analyses. These analyses conclude that body shape is most strongly predicted by feeding preferences (i.e., trophic niches) and the water depths at which species occur. Furthermore, the morphological disparity within tribes indicates that even though the morphological diversification associated with explosive speciation has happened in only a few tribes of the Tanganyikan assemblage, the potential to evolve diverse morphologies exists in all tribes. Quantitative data support the existence of extensive parallelism in several independent adaptive radiations in Lake Tanganyika. Notably, Tanganyikan mouthbrooders belonging to the C-lineage and the substrate spawning Lamprologini have evolved a multitude of different shapes from elongated and Lamprologus-like hypothetical ancestors. Together, these data demonstrate strong support for the adaptive character of East African cichlid radiations.

Microhabitat use, diet, and performance data on the Hispaniolan twig anole, Anolis sheplani: Pushing the boundaries of morphospace

Caribbean Anolis lizards are often cited as a textbook example of adaptive radiation. Similar morphologies (ecomorphs) have originated in similar ecological settings on different large islands in the West Indies. However, relatively little is known about one of the morphologically most specialized and divergent ecomorphs: the twig anoles. Here, we investigate aspects of morphology, dewlap size, locomotor and bite performance, structural habitat and diet of the poorly known twig anole, Anolis sheplani from Hispaniola. Few observations have previously been made of this species in its natural habitat, and few quantitative data on its natural history are available. A. sheplani is an extreme twig anole with respect to its morphology, performance capacities, and ecological niche. Males and females of this species do not differ from each other in body dimensions, performance or habitat use, but males do have a bigger dewlap than females. We present data for 25 individuals and compare them with data for other Greater Antillean anoles. It becomes apparent that twig anoles constitute a large component of the morphological, functional, and ecological diversity of Anolis lizards. Small twig anoles such as A. sheplani appear to be pushing the boundaries of morphospace and are thus crucial in our understanding of the evolution of phenotypic diversity.

The calmodulin pathway and evolution of elongated beak morphology in Darwin's finches

A classic textbook example of adaptive radiation under natural selection is the evolution of 14 closely related species of Darwin's finches (Fringillidae, Passeriformes), whose primary diversity lies in the size and shape of their beaks. Thus, ground finches have deep and wide beaks, cactus finches have long and pointed beaks (low depth and narrower width), and warbler finches have slender and pointed beaks, reflecting differences in their respective diets. Previous work has shown that even small differences in any of the three major dimensions (depth, width and length) of the beak have major consequences for the overall fitness of the birds. Recently we used a candidate gene approach to explain one pathway involved in Darwin's finch beak morphogenesis. However, this type of analysis is limited to molecules with a known association with craniofacial and/or skeletogenic development. Here we use a less constrained, complementary DNA microarray analysis of the transcripts expressed in the beak primordia to find previously unknown genes and pathways whose expression correlates with specific beak morphologies. We show that calmodulin (CaM), a molecule involved in mediating Ca2+ signalling, is expressed at higher levels in the long and pointed beaks of cactus finches than in more robust beak types of other species. We validated this observation with in situ hybridizations. When this upregulation of the CaM-dependent pathway is artificially replicated in the chick frontonasal prominence, it causes an elongation of the upper beak, recapitulating the beak morphology of the cactus finches. Our results indicate that local upregulation of the CaM-dependent pathway is likely to have been a component of the evolution of Darwin's finch species with elongated beak morphology and provide a mechanistic explanation for the independence of beak evolution along different axes. More generally, our results implicate the CaM-dependent pathway in the developmental regulation of craniofacial skeletal structures.

CONTRASTING PATTERNS AND PROCESSES OF EVOLUTIONARY CHANGE IN THE TARWEED–SILVERSWORD LINEAGE: REVISITING CLAUSEN, KECK, AND HIESEY'S FINDINGS1

Abstract Jens C. Clausen, David D. Keck, and William M. Hiesey's biosystematic research on continental tarweeds (Madiinae; Compositae) provided diverse examples of evolutionary change for Clausen's synthesis, Stages in the Evolution of Plant Species. Subsequent anatomical work by Sherwin Carlquist demonstrated that the tarweed lineage also includes a spectacular example of adaptive radiation, the Hawaiian silversword alliance. Molecular phylogenetic data and evidence from genetic and hybridization studies have allowed additional perspectives on Clausen et al.'s and Carlquist's hypotheses of tarweed–silversword evolution. In Californian Layia, Clausen et al.'s evidence for gradual allopatric diversification for the n = 7 taxa accords with patterns of molecular divergence and decay of interfertility across lineages inferred from a rate-constant rDNA tree. In contrast, recent evidence on patterns and timing of diversification in an n = 8 Layia clade indicates multiple examples of accelerated phenotypic evolu...

Coexistence and differentiation of ‘flowering stones’: the role of local adaptation to soil microenvironment

Summary 1 In most documented examples of adaptive radiation, the processes driving divergence of phenotypes and, ultimately, speciation remain speculative. The remarkable radiation of the Aizoaceae in the southern African winter-rainfall deserts is no exception. 2 We examined the role of specialization to soil microenvironments in the coexistence and differentiation of the aizoaceous genus Argyroderma, which is confined to quartz-lag gravel habitat in southern Africa. 3 We examined patterns of edaphic habitat use and morphological divergence between three sympatrically occurring species (one habitat generalist and two quartz specialists) and used transplant experiments to investigate the extent of local adaptation to quartz microenvironments. 4 Soils utilized by populations of the generalist, A. fissum, and one of the specialists, A. pearsonii, differ significantly in terms of stone content and quartz cover. The soils utilized by the two specialist taxa (A. pearsonii and A. delaetii) do not differ significantly in terms of the variables measured, although A. pearsonii consistently uses habitats with higher quartz cover at all contact zones investigated. 5 The three species are clearly separated morphologically. The morphological trend between Argyroderma species occupying sparse (A. fissum) and dense (A. pearsonii and A. delaetii) quartz habitats is towards reduction in plant size and height (dwarfism), increased levels of submergence, decreased branching, spherical leaf shapes, increased leaf thickness and increased enclosure of the leaf by the old leaf sheaths. The two specialist taxa differ in terms of leaf sheath enclosure, plant submergence and fruit traits. 6 Transplant experiments demonstrate home-site survival advantage in transplants between species occupying sparse and dense quartz habitats as well as between microenvironments within the dense quartz habitat. 7 The results suggest that divergence in potentially functional morphological traits between Argyroderma species occupying different edaphic microenvironments probably results from local adaptation, with coexistence facilitated by response to fine-scale habitat variation. In addition, the results suggest a possible role for edaphic specialization in the evolutionary divergence of Argyroderma and perhaps in the broader radiation of the Aizoaceae in southern Africa.

Colour-assortative mating among populations of Tropheus moorii, a cichlid fish from Lake Tanganyika, East Africa.

The species flocks of cichlid fishes in the East African Lakes Tanganyika, Malawi and Victoria are prime examples of adaptive radiation and explosive speciation. Several hundreds of endemic species have evolved in each of the lakes over the past several thousands to a few millions years. Sexual selection via colour-assortative mating has often been proposed as a probable causal factor for initiating and maintaining reproductive isolation. Here, we report the consequences of human-mediated admixis among differentially coloured populations of the endemic cichlid fish Tropheus moorii from several localities that have accidentally been put in sympatry in a small harbour bay in the very south of Lake Tanganyika. We analysed the phenotypes (coloration) and genotypes (mitochondrial control region and five microsatellite loci) of almost 500 individuals, sampled over 3 consecutive years. Maximum-likelihood-based parenthood analyses and Bayesian inference of population structure revealed that significantly more juveniles are the product of within-colour-morph matings than could be expected under the assumption of random mating. Our results clearly indicate a marked degree of assortative mating with respect to the different colour morphs. Therefore, we postulate that sexual selection based on social interactions and female mate choice has played an important role in the formation and maintenance of the different colour morphs in Tropheus, and is probably common in other maternally mouthbrooding cichlids as well.

Darwin’s finches

Darwin’s finches