scholarly journals Bridging the Process-Pattern Divide to Understand the Origins and Early Stages of Adaptive Radiation: A Review of Approaches With Insights From Studies of Anolis Lizards

2019 ◽  
Vol 111 (1) ◽  
pp. 33-42 ◽  
Author(s):  
James T Stroud ◽  
Jonathan B Losos
Keyword(s):  
Adaptive Radiation ◽  
Biological Diversity ◽  
Greater Antilles ◽  
Adaptive Diversification ◽  
Early Stages ◽  
Process Pattern ◽  
Alternative Approach ◽  
Adaptive Radiations ◽  
Underlying Processes ◽  
Radiation Research

Abstract Understanding the origins and early stages of diversification is one of the most elusive tasks in adaptive radiation research. Classical approaches, which aim to infer past processes from present-day patterns of biological diversity, are fraught with difficulties and assumptions. An alternative approach has been to study young clades of relatively few species, which may represent the putative early stages of adaptive radiation. However, it is difficult to predict whether those groups will ever reach the ecological and morphological disparity observed in the sorts of clades usually referred to as adaptive radiations, thereby making their utility in informing the early stages of such radiations uncertain. Caribbean Anolis lizards are a textbook example of an adaptive radiation; anoles have diversified independently on each of the 4 islands in the Greater Antilles, producing replicated radiations of phenotypically diverse species. However, the underlying processes that drove these radiations occurred 30–65 million years ago and so are unobservable, rendering major questions about how these radiations came to be difficult to tackle. What did the ancestral species of the anole radiation look like? How did new species arise? What processes drove adaptive diversification? Here, we review what we have learned about the cryptic early stages of adaptive radiation from studies of Anolis lizards, and how these studies have attempted to bridge the process-pattern divide of adaptive radiation research. Despite decades of research, however, fundamental questions linking eco-evolutionary processes to macroevolutionary patterns in anoles remain difficult to answer.

scholarly journals Radula diversification promotes ecomorph divergence in an adaptive radiation of freshwater snails

2020 ◽  
Author(s):  
Leon Hilgers ◽  
Stefanie Hartmann ◽  
Jobst Pfaender ◽  
Nora Lentge-Maaß ◽  
Thomas von Rintelen ◽  
...  
Keyword(s):  
Adaptive Radiation ◽  
Complex Traits ◽  
Molecular Basis ◽  
Molecular Mechanisms ◽  
Freshwater Snail ◽  
Freshwater Snails ◽  
Trophic Specialization ◽  
Adaptive Diversification ◽  
Adaptive Radiations ◽  
Lineage Divergence

AbstractAdaptive diversification of complex traits plays a pivotal role for the evolution of organismal diversity. However, the underlying molecular mechanisms remain largely elusive. In the freshwater snail genus Tylomelania, adaptive radiations were likely promoted by trophic specialization via diversification of their key foraging organ, the radula. To investigate the molecular basis of radula diversification and its contribution to lineage divergence, we use pooled tissue-specific transcriptomes of two sympatric Tylomelania sarasinorum ecomorphs. We show that divergence in both gene expression and coding sequences is stronger between radula transcriptomes compared to mantle and foot transcriptomes. These findings support the hypothesis that diversifying selection on the radula is driving speciation in Tylomelania radiations. We also identify several candidate genes for radula divergence. Putative homologs of some candidates (hh, arx, gbb) also contributed to trophic specialization in cichlids and Darwin’s finches, indicating that some molecular pathways may be especially prone to adaptive diversification.

scholarly journals Divergence, Convergence and Phenotypic Diversity of Neotropical Frugivorous Bats

Diversity ◽  
2018 ◽  
Vol 10 (3) ◽  
pp. 100 ◽  
Author(s):  
Oscar Murillo-García ◽  
Maria De la vega
Keyword(s):  
Biological Diversity ◽  
Phenotypic Diversity ◽  
Morphological Evolution ◽  
Strong Association ◽  
Diverse Group ◽  
Skull Morphology ◽  
Adaptive Diversification ◽  
Phenotypic Divergence ◽  
Adaptive Radiations ◽  
Morphological Innovation

Knowing how adaptation shapes morphological evolution is fundamental to understanding the processes that promote biological diversity. However, there is a lack of empirical evidence on the effects of adaptive radiations on phenotypic diversity, which is related to processes that promote phenotypic divergence and convergence. We applied comparative methods to identify shifts in adaptive peaks and to detect divergence and convergence in skull morphology of frugivorous bats (Phyllostomidae: Stenodermatinae and Carollinae), an ecologically diverse group with strong association between skull morphology, feeding performance and diet that suggests adaptive diversification through morphological innovation. We found divergence and convergence for skull morphology. Fifteen peak shifts were found for jaws, which result in four convergent and four divergent regimes. For skull, nine peak shifts were detected that result in three convergent and three divergent regimes. Furthermore, convergence was significant and strong for skull morphology since distantly related organisms converged to the same adaptive optima. Results suggest that convergence indicates the effect of restriction on phenotypes to keep the advantages provided by the skull phenotype that played a central role in the evolution of strict frugivory in phyllostomids. We conclude that convergence has limited phenotypic diversity of functional traits related to feeding in phyllostomid frugivores.

scholarly journals Adaptive radiation and hybridization in Wallace's Dreamponds: evidence from sailfin silversides in the Malili Lakes of Sulawesi

2006 ◽  
Vol 273 (1598) ◽  
pp. 2209-2217 ◽  
Author(s):  
Fabian Herder ◽  
Arne W Nolte ◽  
Jobst Pfaender ◽  
Julia Schwarzer ◽  
Renny K Hadiaty ◽  
...  
Keyword(s):  
New Species ◽  
Adaptive Radiation ◽  
Introgressive Hybridization ◽  
Reticulate Evolution ◽  
Species Group ◽  
Potential Force ◽  
Major Interest ◽  
Key Factor ◽  
Adaptive Radiations ◽  
Malili Lakes

Adaptive radiations are extremely useful to understand factors driving speciation. A challenge in speciation research is to distinguish forces creating novelties and those relevant to divergence and adaptation. Recently, hybridization has regained major interest as a potential force leading to functional novelty and to the genesis of new species. Here, we show that introgressive hybridization is a prominent phenomenon in the radiation of sailfin silversides (Teleostei: Atheriniformes: Telmatherinidae) inhabiting the ancient Malili Lakes of Sulawesi, correlating conspicuously with patterns of increased diversity. We found the most diverse lacustrine species-group of the radiation to be heavily introgressed by genotypes originating from streams of the lake system, an effect that has masked the primary phylogenetic pattern of the flock. We conclude that hybridization could have acted as a key factor in the generation of the flock's spectacular diversity. To our knowledge, this is the first empirical evidence for massive reticulate evolution within a complex animal radiation.

scholarly journals Origin, adaptive radiation and diversification of the Hawaiian lobeliads (Asterales: Campanulaceae)

2008 ◽  
Vol 276 (1656) ◽  
pp. 407-416 ◽  
Author(s):  
Thomas J Givnish ◽  
Kendra C Millam ◽  
Austin R Mast ◽  
Thomas B Paterson ◽  
Terra J Theim ◽  
...  
Keyword(s):  
Molecular Phylogeny ◽  
Tropical Forests ◽  
Adaptive Radiation ◽  
Growth Form ◽  
Oceanic Island ◽  
Tube Length ◽  
Tropical Plants ◽  
Limited Dispersal ◽  
Adaptive Radiations ◽  
Morphological Differences

The endemic Hawaiian lobeliads are exceptionally species rich and exhibit striking diversity in habitat, growth form, pollination biology and seed dispersal, but their origins and pattern of diversification remain shrouded in mystery. Up to five independent colonizations have been proposed based on morphological differences among extant taxa. We present a molecular phylogeny showing that the Hawaiian lobeliads are the product of one immigration event; that they are the largest plant clade on any single oceanic island or archipelago; that their ancestor arrived roughly 13 Myr ago; and that this ancestor was most likely woody, wind-dispersed, bird-pollinated, and adapted to open habitats at mid-elevations. Invasion of closed tropical forests is associated with evolution of fleshy fruits. Limited dispersal of such fruits in wet-forest understoreys appears to have accelerated speciation and led to a series of parallel adaptive radiations in Cyanea , with most species restricted to single islands. Consistency of Cyanea diversity across all tall islands except Hawai i suggests that diversification of Cyanea saturates in less than 1.5 Myr. Lobeliad diversity appears to reflect a hierarchical adaptive radiation in habitat, then elevation and flower-tube length, and provides important insights into the pattern and tempo of diversification in a species-rich clade of tropical plants.

scholarly journals Cranial shape evolution in adaptive radiations of birds: comparative morphometrics of Darwin's finches and Hawaiian honeycreepers

2017 ◽  
Vol 372 (1713) ◽  
pp. 20150481 ◽  
Author(s):  
Masayoshi Tokita ◽  
Wataru Yano ◽  
Helen F. James ◽  
Arhat Abzhanov
Keyword(s):  
Adaptive Radiation ◽  
Molecular Mechanisms ◽  
Rapid Evolution ◽  
Oceanic Islands ◽  
Shape Variation ◽  
Skull Morphology ◽  
Darwin's Finches ◽  
Hawaiian Honeycreepers ◽  
Darwin’S Finches ◽  
Adaptive Radiations

Adaptive radiation is the rapid evolution of morphologically and ecologically diverse species from a single ancestor. The two classic examples of adaptive radiation are Darwin's finches and the Hawaiian honeycreepers, which evolved remarkable levels of adaptive cranial morphological variation. To gain new insights into the nature of their diversification, we performed comparative three-dimensional geometric morphometric analyses based on X-ray microcomputed tomography (µCT) scanning of dried cranial skeletons. We show that cranial shapes in both Hawaiian honeycreepers and Coerebinae (Darwin's finches and their close relatives) are much more diverse than in their respective outgroups, but Hawaiian honeycreepers as a group display the highest diversity and disparity of all other bird groups studied. We also report a significant contribution of allometry to skull shape variation, and distinct patterns of evolutionary change in skull morphology in the two lineages of songbirds that underwent adaptive radiation on oceanic islands. These findings help to better understand the nature of adaptive radiations in general and provide a foundation for future investigations on the developmental and molecular mechanisms underlying diversification of these morphologically distinguished groups of birds. This article is part of the themed issue ‘Evo-devo in the genomics era, and the origins of morphological diversity’.

scholarly journals Iterative adaptive radiations of fossil canids show no evidence for diversity-dependent trait evolution

2015 ◽  
Vol 112 (16) ◽  
pp. 4897-4902 ◽  
Author(s):  
Graham J. Slater
Keyword(s):  
Adaptive Radiation ◽  
Morphological Evolution ◽  
Empirical Support ◽  
Phenotypic Evolution ◽  
Ecological Opportunity ◽  
Radiation Theory ◽  
Molar Teeth ◽  
Adaptive Radiations ◽  
Adaptive Peak ◽  
Adaptive Zone

A long-standing hypothesis in adaptive radiation theory is that ecological opportunity constrains rates of phenotypic evolution, generating a burst of morphological disparity early in clade history. Empirical support for the early burst model is rare in comparative data, however. One possible reason for this lack of support is that most phylogenetic tests have focused on extant clades, neglecting information from fossil taxa. Here, I test for the expected signature of adaptive radiation using the outstanding 40-My fossil record of North American canids. Models implying time- and diversity-dependent rates of morphological evolution are strongly rejected for two ecologically important traits, body size and grinding area of the molar teeth. Instead, Ornstein–Uhlenbeck processes implying repeated, and sometimes rapid, attraction to distinct dietary adaptive peaks receive substantial support. Diversity-dependent rates of morphological evolution seem uncommon in clades, such as canids, that exhibit a pattern of replicated adaptive radiation. Instead, these clades might best be thought of as deterministic radiations in constrained Simpsonian subzones of a major adaptive zone. Support for adaptive peak models may be diagnostic of subzonal radiations. It remains to be seen whether early burst or ecological opportunity models can explain broader adaptive radiations, such as the evolution of higher taxa.

scholarly journals Hybrid misexpression in multiple developing tissues within a recent adaptive radiation of Cyprinodon pupfishes

2018 ◽  
Author(s):  
Joseph A. McGirr ◽  
Christopher H. Martin
Keyword(s):  
Adaptive Radiation ◽  
Craniofacial Morphology ◽  
Differentially Expressed ◽  
The Novel ◽  
Specific Expression ◽  
Developmental Networks ◽  
Allele Specific ◽  
Adaptive Radiations ◽  
Craniofacial Tissue ◽  
Compare Gene Expression

AbstractGenetic incompatibilities constitute the final stages of reproductive isolation and speciation, but little is known about incompatibilities that occur within recent adaptive radiations among closely related diverging populations. Crossing divergent species to form hybrids can break up coadapted variation, resulting in genetic incompatibilities within developmental networks shaping adaptive traits. We crossed two closely related sympatric Cyprinodon pupfish species – a dietary generalist and a specialized molluscivore – and measured expression levels in their F1 hybrids to identify regulatory variation underlying the novel craniofacial morphology found in this recent microendemic adaptive radiation. We extracted mRNA from eight day old whole-larvae tissue and from craniofacial tissues dissected from 17-20 day old larvae to compare gene expression between a total of seven F1 hybrids and 24 individuals from parental species populations. We found 3.9% of genes differentially expressed between generalists and molluscivores in whole-larvae tissues and 0.6% of genes differentially expressed in craniofacial tissue. We found that 2.1% of genes were misexpressed in whole-larvae hybrids at 8 dpf whereas 19.1% of genes were misexpressed in hybrid craniofacial tissue at 17-20 dpf, after correcting for sequencing biases. We also measured allele specific expression across 15,429 phased heterozygous sites to identify regulatory mechanisms underlying differential expression between generalists and molluscivores. Together, our results highlight the importance of considering misexpression as an early indicator of genetic incompatibilities in the context of rapidly diverged morphology and suggests that wide-spread compensatory regulatory divergence drives hybrid misexpression in developing tissues that give rise to novel craniofacial traits.

scholarly journals Parallel and non-parallel changes of the gut microbiota during trophic diversification in repeated young adaptive radiations of sympatric cichlid fish

2020 ◽  
Author(s):  
Andreas Härer ◽  
Julián Torres-Dowdall ◽  
Sina J. Rometsch ◽  
Elizabeth Yohannes ◽  
Gonzalo Machado-Schiaffino ◽  
...  
Keyword(s):  
Gut Microbiota ◽  
Microbial Communities ◽  
Trophic Ecology ◽  
Cichlid Fish ◽  
Conclusive Evidence ◽  
Rrna Gene ◽  
Crater Lakes ◽  
Ecological Diversification ◽  
Early Stages ◽  
Adaptive Radiations

Abstract Background: Recent increases in understanding the ecological and evolutionary roles of microbial communities has underscored the importance for their hosts’ biology. Yet, little is known about gut microbiota dynamics during early stages of ecological diversification and speciation. We sequenced the V4 region of the 16s rRNA gene to study the gut microbiota of Nicaraguan Midas cichlid fish (Amphilophus cf. citrinellus). Specifically, we tested the hypothesis that parallel divergence in trophic ecology in extremely young adaptive radiations from two crater lakes is associated with parallel changes of their gut microbiota. Results: Bacterial communities of fish guts and lake water were highly distinct, indicating that the gut microbiota is shaped by host-specific factors. Among individuals of the same crater lake, differentiation in trophic ecology was weakly associated with gut microbiota differentiation, suggesting that diet, to some extent, affects the gut microbiota. However, differences in trophic ecology were much more pronounced across than within species whereas similar patterns were not observed for taxonomic and functional differences of the gut microbiota. Across the two crater lakes, we could not detect conclusive evidence for parallel changes of the gut microbiota associated with trophic ecology. Conclusions: A lack of clearly differentiated niches during early stages of ecological diversification might result in non-parallel changes of gut microbial communities, as observed in our study system as well as in other recently diverged fish species.

scholarly journals Ancestral polymorphisms shape the adaptive radiation of Metrosideros across the Hawaiian Islands

2021 ◽  
Vol 118 (37) ◽  
pp. e2023801118
Author(s):  
Jae Young Choi ◽  
Xiaoguang Dai ◽  
Ornob Alam ◽  
Julie Z. Peng ◽  
Priyesh Rughani ◽  
...  
Keyword(s):  
Genome Assembly ◽  
Adaptive Radiation ◽  
Evolutionary Biology ◽  
Population Genomics ◽  
Hawaiian Islands ◽  
Divergent Selection ◽  
Metrosideros Polymorpha ◽  
Nucleotide Polymorphisms ◽  
Founder Populations ◽  
Adaptive Radiations

Some of the most spectacular adaptive radiations begin with founder populations on remote islands. How genetically limited founder populations give rise to the striking phenotypic and ecological diversity characteristic of adaptive radiations is a paradox of evolutionary biology. We conducted an evolutionary genomics analysis of genus Metrosideros, a landscape-dominant, incipient adaptive radiation of woody plants that spans a striking range of phenotypes and environments across the Hawaiian Islands. Using nanopore-sequencing, we created a chromosome-level genome assembly for Metrosideros polymorpha var. incana and analyzed whole-genome sequences of 131 individuals from 11 taxa sampled across the islands. Demographic modeling and population genomics analyses suggested that Hawaiian Metrosideros originated from a single colonization event and subsequently spread across the archipelago following the formation of new islands. The evolutionary history of Hawaiian Metrosideros shows evidence of extensive reticulation associated with significant sharing of ancestral variation between taxa and secondarily with admixture. Taking advantage of the highly contiguous genome assembly, we investigated the genomic architecture underlying the adaptive radiation and discovered that divergent selection drove the formation of differentiation outliers in paired taxa representing early stages of speciation/divergence. Analysis of the evolutionary origins of the outlier single nucleotide polymorphisms (SNPs) showed enrichment for ancestral variations under divergent selection. Our findings suggest that Hawaiian Metrosideros possesses an unexpectedly rich pool of ancestral genetic variation, and the reassortment of these variations has fueled the island adaptive radiation.

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