scholarly journals Possible human impacts on adaptive radiation: beak size bimodality in Darwin's finches

2006 ◽  
Vol 273 (1596) ◽  
pp. 1887-1894 ◽  
Author(s):  
Andrew P Hendry ◽  
Peter R Grant ◽  
B Rosemary Grant ◽  
Hugh A Ford ◽  
Mark J Brewer ◽  
...  
Keyword(s):  
Adaptive Radiation ◽  
Human Activities ◽  
Human Impacts ◽  
Adaptive Landscape ◽  
Hybrid Fitness ◽  
Evolutionary Diversification ◽  
Adaptive Landscapes ◽  
Adaptive Radiations ◽  
Geospiza Fortis ◽  
Beak Size

Adaptive radiation is facilitated by a rugged adaptive landscape, where fitness peaks correspond to trait values that enhance the use of distinct resources. Different species are thought to occupy the different peaks, with hybrids falling into low-fitness valleys between them. We hypothesize that human activities can smooth adaptive landscapes, increase hybrid fitness and hamper evolutionary diversification. We investigated this possibility by analysing beak size data for 1755 Geospiza fortis measured between 1964 and 2005 on the island of Santa Cruz, Galápagos. Some populations of this species can display a resource-based bimodality in beak size, which mirrors the greater beak size differences among species. We first show that an historically bimodal population at one site, Academy Bay, has lost this property in concert with a marked increase in local human population density. We next show that a nearby site with lower human impacts, El Garrapatero, currently manifests strong bimodality. This comparison suggests that bimodality can persist when human densities are low (Academy Bay in the past, El Garrapatero in the present), but not when they are high (Academy Bay in the present). Human activities may negatively impact diversification in ‘young’ adaptive radiations, perhaps by altering adaptive landscapes.

scholarly journals Acoustic discrimination of sympatric morphs in Darwin's finches: a behavioural mechanism for assortative mating?

2010 ◽  
Vol 365 (1543) ◽  
pp. 1031-1039 ◽  
Author(s):  
Jeffrey Podos
Keyword(s):  
Assortative Mating ◽  
Disruptive Selection ◽  
Evolutionary Divergence ◽  
Santa Cruz Island ◽  
Evolutionary Diversification ◽  
Acoustic Discrimination ◽  
Behavioural Types ◽  
Geospiza Fortis ◽  
Beak Size ◽  
Behavioural Mechanism

Populations with multiple morphological or behavioural types provide unique opportunities for studying the causes and consequences of evolutionary diversification. A population of the medium ground finch ( Geospiza fortis ) at El Garrapatero on Santa Cruz Island, Galápagos, features two beak size morphs. These morphs produce acoustically distinctive songs, are subject to disruptive selection and mate assortatively by morph. The main goal of the present study was to assess whether finches from this population are able to use song as a cue for morph discrimination. A secondary goal of this study was to evaluate whether birds from this population discriminate songs of their own locality versus another St Cruz locality, Borrero Bay, approximately 24 km to the NW. I presented territorial males with playback of songs of their own morph, of the other morph, and of males from Borrero Bay. Males responded more strongly to same-morph than to other-morph playbacks, showing significantly shorter latencies to flight, higher flight rates and closer approaches to the playback speaker. By contrast, I found only minor effects of locality on responsiveness. Evidence for morph discrimination via acoustic cues supports the hypothesis that song can serve as a behavioural mechanism for assortative mating and sympatric evolutionary divergence.

scholarly journals Island- and lake-like parallel adaptive radiations replicated in rivers

2018 ◽  
Vol 285 (1870) ◽  
pp. 20171762 ◽  
Author(s):  
Edward D. Burress ◽  
Lubomír Piálek ◽  
Jorge R. Casciotta ◽  
Adriana Almirón ◽  
Milton Tan ◽  
...  
Keyword(s):  
Adaptive Radiation ◽  
Novel Ecosystems ◽  
South American ◽  
Phenotypic Evolution ◽  
Cichlid Fishes ◽  
Adaptive Landscapes ◽  
Adaptive Radiations

Parallel adaptive radiations have arisen following the colonization of islands by lizards and lakes by fishes. In these classic examples, parallel adaptive radiation is a response to the ecological opportunities afforded by the colonization of novel ecosystems and similar adaptive landscapes that favour the evolution of similar suites of ecomorphs, despite independent evolutionary histories. Here, we demonstrate that parallel adaptive radiations of cichlid fishes arose in South American rivers. Speciation-assembled communities of pike cichlids ( Crenicichla ) have independently diversified into similar suites of novel ecomorphs in the Uruguay and Paraná Rivers, including crevice feeders, periphyton grazers and molluscivores. There were bursts in phenotypic evolution associated with the colonization of each river and the subsequent expansion of morphospace following the evolution of the ecomorphs. These riverine clades demonstrate that characteristics emblematic of textbook parallel adaptive radiations of island- and lake-dwelling assemblages are feasible evolutionary outcomes even in labile ecosystems such as rivers.

scholarly journals What constrains adaptive radiation? Documentation and explanation of under-evolved morphologies in Anolis lizards

2021 ◽  
Vol 288 (1953) ◽  
pp. 20210340
Author(s):  
Steven Poe ◽  
Lorenzo A. H. Donald ◽  
Christopher Anderson
Keyword(s):  
Body Length ◽  
Adaptive Radiation ◽  
Tail Length ◽  
Evolutionary Diversification ◽  
Selective Forces ◽  
Adaptive Radiations

Adaptive radiations fill ecological and morphological space during evolutionary diversification. Why do some trait combinations evolve during such radiations, whereas others do not? ‘Required’ constraints of pleiotropy and developmental interaction frequently are implicated in explanations for such patterns, but selective forces also may discourage particular trait combinations. Here, we use a dataset of 351 species to demonstrate the dearth of some theoretically plausible trait combinations of limb, toe and tail length in Anolis lizards. For example, disproportionately few Anolis species display long limbs and short toes. We evaluate recovered patterns within three species of Anolis , and find that cladewide patterns are not evident at intraspecific levels. For example, within species, the combination of long limbs and short toes is not significantly rarer than long limbs and long toes. Differences in scale complicate inter- and intraspecific comparisons and disallow concrete conclusions of cause. However, the absence of the interspecific pattern at the intraspecific level is more compatible with selection favouring particular trait combinations than with ‘required’ forces dictating which trait combinations are available for selection. We also demonstrate the isometry of toe, tail and hindlimb length relative to body length between species but allometry in four of nine trait–body comparisons within species.

scholarly journals Disruptive selection in a bimodal population of Darwin's finches

2008 ◽  
Vol 276 (1657) ◽  
pp. 753-759 ◽  
Author(s):  
Andrew P Hendry ◽  
Sarah K Huber ◽  
Luis F De León ◽  
Anthony Herrel ◽  
Jeffrey Podos
Keyword(s):  
Adaptive Radiation ◽  
Spatial And Temporal Variation ◽  
Disruptive Selection ◽  
Adaptive Divergence ◽  
Santa Cruz Island ◽  
Santa Cruz ◽  
Prolonged Drought ◽  
Geospiza Fortis ◽  
Beak Size ◽  
Insight Into

A key part of the ecological theory of adaptive radiation is disruptive selection during periods of sympatry. Some insight into this process might be gained by studying populations that are bimodal for dual-context traits, i.e. those showing adaptive divergence and also contributing to reproductive isolation. A population meeting these criteria is the medium ground finch ( Geospiza fortis ) of El Garrapatero, Santa Cruz Island, Galápagos. We examined patterns of selection in this population by relating individual beak sizes to interannual recaptures during a prolonged drought. Supporting the theory, disruptive selection was strong between the two beak size modes. We also found some evidence of selection against individuals with the largest and smallest beak sizes, perhaps owing to competition with other species or to gaps in the underlying resource distribution. Selection may thus simultaneously maintain the current bimodality while also constraining further divergence. Spatial and temporal variation in G. fortis bimodality suggests a dynamic tug of war among factors such as selection and assortative mating, which may alternatively promote or constrain divergence during adaptive radiation.

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 Role of sexual imprinting in assortative mating and premating isolation in Darwin’s finches

2018 ◽  
Vol 115 (46) ◽  
pp. E10879-E10887 ◽  
Author(s):  
Peter R. Grant ◽  
B. Rosemary Grant
Keyword(s):  
Natural Habitat ◽  
Good Choice ◽  
Premating Isolation ◽  
Sexual Imprinting ◽  
Darwin's Finches ◽  
Darwin’S Finches ◽  
Adaptive Radiations ◽  
Beak Size ◽  
Species Specific

Global biodiversity is being degraded at an unprecedented rate, so it is important to preserve the potential for future speciation. Providing for the future requires understanding speciation as a contemporary ecological process. Phylogenetically young adaptive radiations are a good choice for detailed study because diversification is ongoing. A key question is how incipient species become reproductively isolated from each other. Barriers to gene exchange have been investigated experimentally in the laboratory and in the field, but little information exists from the quantitative study of mating patterns in nature. Although the degree to which genetic variation underlying mate-preference learning is unknown, we provide evidence that two species of Darwin’s finches imprint on morphological cues of their parents and mate assortatively. Statistical evidence of presumed imprinting is stronger for sons than for daughters and is stronger for imprinting on fathers than on mothers. In combination, morphology and species-specific song learned from the father constitute a barrier to interbreeding. The barrier becomes stronger the more the species diverge morphologically and ecologically. It occasionally breaks down, and the species hybridize. Hybridization is most likely to happen when species are similar to each other in adaptive morphological traits, e.g., body size and beak size and shape. Hybridization can lead to the formation of a new species reproductively isolated from the parental species as a result of sexual imprinting. Conservation of sufficiently diverse natural habitat is needed to sustain a large sample of extant biota and preserve the potential for future speciation.

scholarly journals Human impacts and their interactions in the Baltic Sea region

2021 ◽  
Author(s):  
Marcus Reckermann ◽  
Anders Omstedt ◽  
Tarmo Soomere ◽  
Juris Aigars ◽  
Naveed Akhtar ◽  
...  
Keyword(s):  
Climate Change ◽  
Baltic Sea ◽  
Human Activities ◽  
Human Impacts ◽  
The Other ◽  
Indigenous Species ◽  
General Description ◽  
The Baltic Sea ◽  
Baltic Sea Region ◽  
The Baltic

Abstract. Coastal environments, in particular heavily populated semi-enclosed marginal seas and coasts like the Baltic Sea region, are stongly affected by human activities. A multitude of human impacts, including climate change, affects the different compartments of the environment, and these effects interact with each other. As part of the Baltic Earth Assessment Reports (BEAR), we present an inventory and discussion of different human-induced factors and processes affecting the environment of the Baltic Sea region, and their interrelations. Some are naturally occurring and modified by human activities (i.e. climate change, coastal processes, hypoxia, acidification, submarine groundwater discharges, marine ecosystems, non-indigenous species, land use and land cover), some are completely human-induced (i.e. agriculture, aquaculture, fisheries, river regulations, offshore wind farms, shipping, chemical contamination, dumped warfare agents, marine litter and microplastics, tourism, coastal management), and they are all interrelated to different degrees. We present a general description and analysis of the state of knowledge on these interrelations. Our main insight is that climate change has an overarching, integrating impact on all of the other factors and can be interpreted as a background effect, which has different implications for the other factors. Impacts on the environment and the human sphere can be roughly allocated to anthropogenic drivers such as food production, energy production, transport, industry and economy. We conclude that a sound management and regulation of human activities must be implemented in order to use and keep the environments and ecosystems of the Baltic Sea region sustainably in a good shape. This must balance the human needs, which exert tremendous pressures on the systems, as humans are the overwhelming driving force for almost all changes we see. The findings from this inventory of available information and analysis of the different factors and their interactions in the Baltic Sea region can largely be transferred to other comparable marginal and coastal seas in the world.

scholarly journals Who are We, and Who (or What) Do We Want to Become? An Evolutionary Perspective on Biotransformative Technologies

2021 ◽  
Author(s):  
James Lyons-Weiler
Keyword(s):  
Human Evolution ◽  
Adaptive Landscape ◽  
Endogenous Factors ◽  
Theoretical Contribution ◽  
Organic Evolution ◽  
Adaptive Landscapes ◽  
Augmented Cognition ◽  
Language Writing ◽  
Cognitive Plasticity ◽  
The Impact

AbstractHuman evolution sits at several important thresholds. In organic evolution, interplay between exogenous environmental and genetic factors rendered new phenotypes at rates limited by genetic variation. The interplay took place on adaptive fitness landscapes determined by correspondence of genetic and environmental relationships. Human evolution involved important emergences that altered the adaptive landscape: language, writing, organized societies, science, and the internet. These endogenous factors ushered in transformative periods leading to more rapidly evolving emergences. I explore the impact of development of emerging biotransformative technologies capable of being applied to effect self-genetic modification and artificial intelligence-augmented cognition on the evolutionary landscape of phenotypes important to cognitive plasticity. Interaction effects will yield unanticipated emergences resulting in hyperrealm adaptive landscapes with more rapid evolutionary processes that feed back upon more fundamental levels while vastly outpacing organic evolution. Emerging technologies exist that are likely to impact the evolution of cognitive plasticity in humans in ways and at rates that will lead to societal upheaval. I show that the theoretical contribution of organic evolution in future human evolution is expected to become comparatively insignificant relative to that made by endogenous environmental factors such as external cognition aids and manipulation of the human genome. The results support the conclusion of a strong recommendation of a moratorium on the adoption of any technology capable of completely altering the course of human evolution.

scholarly journals Mapping Cumulative Impacts of Human Activities on Marine Ecosystems

2018 ◽  
Author(s):  
SeaPlan
Keyword(s):  
Human Activities ◽  
Spatial Information ◽  
Human Impacts ◽  
Marine Ecosystems ◽  
Management Plan ◽  
Cumulative Impacts ◽  
Potential Conflict ◽  
Planning Decisions ◽  
Ocean Management ◽  
Survey Results

Given the diversity of human uses and natural resources that converge in coastal waters, the potential independent and cumulative impacts of those uses on marine ecosystems are important to consider during ocean planning. This study was designed to support the development and implementation of the 2009 Massachusetts Ocean Management Plan. Its goal was to estimate and visualize the cumulative impacts of human activities on coastal and marine ecosystems in the state and federal waters off of Massachusetts.For this study, regional ecosystem experts were surveyed to gauge the relative vulnerability of marine ecosystems to current and emerging anthropogenic stressors. Survey results were then combined with spatial information on the distribution of marine ecosystems and human stressors to map cumulative impacts in Massachusetts waters.The study resulted in an ecosystem vulnerability matrix and human impacts maps, which together yield insights into which ecosystems and places are most vulnerable and which human uses, alone and in combination, are putting the most stress on marine ecosystems. These products can be used in a number of ways, including to help clarify ocean planning decisions, identify areas of potential conflict among ocean users and areas that may merit conservation, and assess ecological, economic and social values of particular places.

scholarly journals Peak shifts and extinction under sex-specific selection

2021 ◽  
Author(s):  
Stephen P. De Lisle
Keyword(s):  
Sexual Selection ◽  
Sexual Dimorphism ◽  
Peak Shift ◽  
Adaptive Landscape ◽  
Population Estimates ◽  
Sexual Antagonism ◽  
Adaptive Landscapes ◽  
Quantitative Genetic ◽  
Complex Adaptive ◽  
The Face

AbstractA well-known property of sexual selection combined with a cross sex genetic correlation (rmf), is that it can facilitate a peak shift on the adaptive landscape. How do these diversifying effects of sexual selection +rmf balance with the constraints imposed by such sexual antagonism, to affect macroevolution of sexual dimorphism? Here, I extend existing quantitative genetic models of evolution on complex adaptive landscapes. Beyond recovering classical predictions for the conditions promoting a peak shift, I show that when rmf is moderate to strong, relatively weak sexual selection is required to induce a peak shift in males only. Increasing the strength of sexual leads to a sexually-concordant peak shift, suggesting that macroevolutionary rates of sexual dimorphism may be largely decoupled from the strength of within-population sexual selection. Accounting explicitly for demography further reveals that sex-specific peak shifts may be more likely to be successful than concordant shifts in the face of extinction, especially when natural selection is strong. An overarching conclusion is that macroevolutionary patterns of sexual dimorphism are unlikely to be readily explained by within-population estimates of selection or constraint alone.

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