Connections between species diversity and genetic diversity (original) (raw)
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SYNTHESES Connections between species diversity and genetic diversity
Species diversity and genetic diversity remain the nearly exclusive domains of community ecology and population genetics, respectively, despite repeated recognition in the literature over the past 30 years of close parallels between these two levels of diversity. Species diversity within communities and genetic diversity within populations are hypothesized to co-vary in space or time because of locality characteristics that influence the two levels of diversity via parallel processes, or because of direct effects of one level of diversity on the other via several different mechanisms. Here, we draw on a wide range of studies in ecology and evolution to examine the theoretical underpinnings of these hypotheses, review relevant empirical literature, and outline an agenda for future research. The plausibility of species diversity-genetic diversity relationships is supported by a variety of theoretical and empirical studies, and several recent studies provide direct, though preliminary support. Focusing on potential connections between species diversity and genetic diversity complements other approaches to synthesis at the ecologyevolution interface, and should contribute to conceptual unification of biodiversity research at the levels of genes and species.
A Neutral Theory for Interpreting Correlations between Species and Genetic Diversity in Communities
The American naturalist, 2015
Spatial patterns of biological diversity have been extensively studied in ecology and population genetics, because they reflect the forces acting on biodiversity. A growing number of studies have found that genetic (within-species) and species diversity can be correlated in space (the so-called species-gene diversity correlation [SGDC]), which suggests that they are controlled by nonindependent processes. Positive SGDCs are generally assumed to arise from parallel responses of genetic and species diversity to variation in site size and connectivity. However, this argument implicitly assumes a neutral model that has yet to be developed. Here, we build such a model to predict SGDC in a metacommunity. We describe how SGDC emerges from competition within sites and variation in connectivity and carrying capacity among sites. We then introduce the formerly ignored mutation process, which affects genetic but not species diversity. When mutation rate is low, our model confirms that variatio...
Ecological consequences of genetic diversity
Ecology Letters, 2008
Understanding the ecological consequences of biodiversity is a fundamental challenge. Research on a key component of biodiversity, genetic diversity, has traditionally focused on its importance in evolutionary processes, but classical studies in evolutionary biology, agronomy and conservation biology indicate that genetic diversity might also have important ecological effects. Our review of the literature reveals significant effects of genetic diversity on ecological processes such as primary productivity, population recovery from disturbance, interspecific competition, community structure, and fluxes of energy and nutrients. Thus, genetic diversity can have important ecological consequences at the population, community and ecosystem levels, and in some cases the effects are comparable in magnitude to the effects of species diversity. However, it is not clear how widely these results apply in nature, as studies to date have been biased towards manipulations of plant clonal diversity, and little is known about the relative importance of genetic diversity vs. other factors that influence ecological processes of interest. Future studies should focus not only on documenting the presence of genetic diversity effects but also on identifying underlying mechanisms and predicting when such effects are likely to occur in nature.
Conservation implications of species–genetic diversity correlations
Global Ecology and Conservation, 2014
Despite its importance for the long-term viability of populations and functioning of ecosystems, the genetic diversity of populations is seldom given explicit consideration in conservation prioritization. Research on the species-genetic diversity correlation (SGDC) suggests that species diversity within a community and intrapopulation genetic diversity are positively correlated, due to the parallel influences of environmental characteristics (area, connectivity, and environmental heterogeneity) on both levels of diversity. A positive locality scale SGDC (i.e. α-SGDC) thus provides potential for simultaneous conservation of both species diversity within a locality and intrapopulation genetic diversity. However, caution is needed, since in some situations environmental characteristics can influence species diversity and genetic diversity differently, resulting in a negative α-SGDC. In such cases there can be a conflict between conservation of species diversity within localities and genetic diversity within populations. SGDCs provide useful information also for conservation planning, which considers compositional differences between localities, since the mechanisms behind α-SGDCs can also drive correlations between differentiation of community and genetic compositions (i.e. β-SGDCs). We suggest that emphasizing locality area and connectivity between similar localities in conservation planning best conserves both species and intrapopulation genetic diversity, and that focusing on highly complementary species richness may compromise conservation of genetic diversity.
Genetic Diversity: Esoteric or Essential?
The presence of genetic subdivisions within plant species has been recognized since the early part of this century. More recent experimental work documents diversity in a number of visible (quantitative and single locus) and molecular (enzyme and DNA sequence) characters. Considerations of the spatial distribution-both pattern and scale-of genetic diversity provide another kind of complexity. Patterns of natural diversity are overlain by patterns of habitat loss that are determined by non-biological forces. A review of the literature on intraspecific plant biodiversity offers some insight into situations where detailed genetic studies may be essential to preservation of diversity. Differentiation both between discrete populations and within continuous ones has been demonstrated, especially in response to strong environmental gradients and in species that are short-lived, inbred or clonal. Strategies to preserve wide-ranging vertebrates may maintain sufficient habitat to sustain a wide variety of plants, but two categories of plants could be neglected entirely by this approach. These are habitat specialists (disturbance regimes, edaphic conditions, ephemeral wetlands) and plants with reproductive systems that are asexual, favor selfing, restrict gene flow, require certain sex ratios or are dependent on specific animal pollinators. Plants that fit into these categories warrant a close examination of their genetic architecture and the dynamics of gene flow. Case studies of three habitat specialists found in southern California (Downingia cuspidata, Downingia concolor ssp. brevior and Nolina interrata) are given as examples.
Is there a trade-off between species diversity and genetic diversity in forest tree communities?
The two most important components of biodiversity, species diversity and genetic diversity, have generally been treated as separate topics, although a coordination between both components is believed to be critical for ecosystem stability and resilience. Based on a new trait concept that allows for the assessment of genetic diversity across species, the relationship between species diversity and genetic diversity was examined in eight forest tree communities composed of different tree genera including both climax and pioneer species. It was intended to check whether a trade-off exists between the two diversity components as was found in a few studies on animal species. Using several isozyme-gene systems as genetic markers, the genetic diversity across species within each of the tree communities was determined by two measures, the commonly used intraspecific genetic diversity averaged over species and the recently developed transspecific genetic diversity per species. Both data sets were compared with the corresponding community-specific species diversity resulting in a positive relationship between the two diversity components. A statistically significant positive correlation was established between the transspecific genetic diversity per species and the species diversity for three isozyme-gene systems. Beyond that, consistent results were obtained using different parameters of the diversity measure which characterize the total, the effective and the number of prevalent variants. The number of prevalent variants reflected most significantly the non-randomness of the observed diversity patterns. These findings can be explained by the observation that the pioneer tree species reveal a by far higher genetic diversity than the climax tree species, which means that an increase in species diversity, due to the addition of several pioneer species at the expense of one or two climax species, goes along with an increase in the level of genetic diversity. Forest tree communities with the highest degree of species diversity exhibit therefore the highest transspecific genetic diversity per species. This result was discussed with regard to the particular composition and stability of forest tree communities.
Evolutionary Ecology Research, 2006
Question: How can we link genotypic, phenotypic, individual, population, and community levels of organization so as to illuminate general ecological and evolutionary processes and provide a framework for a quantitative, integrative evolutionary biology? Framework: We introduce an evolutionary framework that maps different levels of biological diversity onto one another. We provide (1) an overview of maps linking levels of biological organization and (2) a guideline of how to analyse the complexity of relationships from genes to population growth. Method: We specify the appropriate levels of biological organization for responses to selection, for opportunities for selection, and for selection itself. We map between them and embed these maps into an ecological setting.
New thoughts on an old riddle: What determines genetic diversity within and between species?
Genomics, 2016
The question of what determines genetic diversity has long remained unsolved by the modern evolutionary theory (MET). However, it has not deterred researchers from producing interpretations of genetic diversity by using MET. We examine the two observations of genetic diversity made in the 1960s that contributed to the development of MET. The interpretations of these observations by MET are widely known to be inadequate. We review the recent progress of an alternative framework, the maximum genetic diversity (MGD) hypothesis, that uses axioms and natural selection to explain the vast majority of genetic diversity as being at equilibrium that is largely determined by organismal complexity. The MGD hypothesis absorbs the proven virtues of MET and considers its assumptions relevant only to a much more limited scope. This new synthesis has accounted for the overlooked phenomenon of progression towards higher complexity, and more importantly, been instrumental in directing productive rese...
Forward from the crossroads of ecology and evolution
Philosophical Transactions of the Royal Society B Biological Sciences 2011 366 1322 1328, 2011
Community genetics is a synthesis of community ecology and evolutionary biology. It examines how genetic variation within a species affects interactions among species to change ecological community structure and diversity. The use of community genetics approaches has greatly expanded in recent years and the evidence for ecological effects of genetic diversity is growing. The goal of current community genetics research is to determine the circumstances in which, and the mechanisms by which community genetic effects occur and is the focus of the papers in this special issue. We bring a new group of researchers into the community genetics fold. Using a mixture of empirical research, literature reviews and theoretical development, we introduce novel concepts and methods that we hope will enable us to develop community genetics into the future.