scholarly journals Polyploidy and elevation contribute to opposing latitudinal gradients in diversification and species richness in lady ferns (Athyriaceae)

2018 ◽  
Author(s):  
Ran Wei ◽  
Richard H. Ree ◽  
Michael A. Sundue ◽  
Xian-Chun Zhang
Keyword(s):  
Species Richness ◽  
Latitudinal Gradients ◽  
State Change ◽  
Diversification Rates ◽  
Rate Shift ◽  
Polymorphic Species ◽  
The Tropics ◽  
Novel Model

In ferns, the temperate-tropical sister clades Athyrium and Diplazium present an opportunity to study a latitudinal contrast in diversification dynamics. We generated a taxonomically expanded molecular chronogram and used macroevolutionary models to analyze how diversification rates have changed through time, across lineages, and in concert with changes in elevation and ploidy. We tested a novel model of cladogenetic state-change in which polyploidy can arise as an infraspecific polymorphism, with diversification parameters distinct from those of pure diploids and polyploids. Both Athyrium and Diplazium accelerated their diversification near the Oligocene-Miocene transition. In Diplazium, the rate shift is older, with subsequent net diversification somewhat slower and suggestive of diversity-dependence. In Athyrium, diversification is faster and associated with higher elevations. In both clades, polyploids have the highest rate of net accumulation but lowest (negative) net diversification, while the converse is true for polymorphic species; diploids have low rates of both net accumulation and diversification. Diversification in Athyrium may have responded to ecological opportunities in expanding temperate habitats during the Neogene, especially in mountains, while the pattern in Diplazium suggests saturation in the tropics. Neopolyploids are generated rapidly, primarily through accelerated cladogenesis in polymorphic species, but are evolutionary dead ends.

scholarly journals Latitudinal gradients in biotic niche breadth vary across ecosystem types

2015 ◽  
Vol 282 (1819) ◽  
pp. 20151589 ◽  
Author(s):  
Alyssa R. Cirtwill ◽  
Daniel B. Stouffer ◽  
Tamara N. Romanuk
Keyword(s):  
Species Richness ◽  
Food Webs ◽  
Niche Breadth ◽  
The Other ◽  
Latitudinal Gradients ◽  
Food Web Structure ◽  
Scaling Relationships ◽  
Web Structure ◽  
Scaling Relationship ◽  
The Tropics

Several properties of food webs—the networks of feeding links between species—are known to vary systematically with the species richness of the underlying community. Under the ‘latitude–niche breadth hypothesis’, which predicts that species in the tropics will tend to evolve narrower niches, one might expect that these scaling relationships could also be affected by latitude. To test this hypothesis, we analysed the scaling relationships between species richness and average generality, vulnerability and links per species across a set of 196 empirical food webs. In estuarine, marine and terrestrial food webs there was no effect of latitude on any scaling relationship, suggesting constant niche breadth in these habitats. In freshwater communities, on the other hand, there were strong effects of latitude on scaling relationships, supporting the latitude–niche breadth hypothesis. These contrasting findings indicate that it may be more important to account for habitat than latitude when exploring gradients in food-web structure.

Metabolic asymmetry and the global diversity of marine predators

Science ◽  
2019 ◽  
Vol 363 (6425) ◽  
pp. eaat4220 ◽  
Author(s):  
John M. Grady ◽  
Brian S. Maitner ◽  
Ara S. Winter ◽  
Kristin Kaschner ◽  
Derek P. Tittensor ◽  
...  
Keyword(s):  
Species Richness ◽  
Spatial Patterns ◽  
Marine Mammals ◽  
Phylogenetic Diversity ◽  
Latitudinal Gradient ◽  
Latitudinal Gradients ◽  
Competitive Interactions ◽  
Marine Predators ◽  
Theoretical Predictions ◽  
The Tropics

Species richness of marine mammals and birds is highest in cold, temperate seas—a conspicuous exception to the general latitudinal gradient of decreasing diversity from the tropics to the poles. We compiled a comprehensive dataset for 998 species of sharks, fish, reptiles, mammals, and birds to identify and quantify inverse latitudinal gradients in diversity, and derived a theory to explain these patterns. We found that richness, phylogenetic diversity, and abundance of marine predators diverge systematically with thermoregulatory strategy and water temperature, reflecting metabolic differences between endotherms and ectotherms that drive trophic and competitive interactions. Spatial patterns of foraging support theoretical predictions, with total prey consumption by mammals increasing by a factor of 80 from the equator to the poles after controlling for productivity.

scholarly journals Unifying latitudinal gradients in range size and richness across marine and terrestrial systems

2016 ◽  
Vol 283 (1830) ◽  
pp. 20153027 ◽  
Author(s):  
Adam Tomašových ◽  
Jonathan D. Kennedy ◽  
Tristan J. Betzner ◽  
Nicole Bitler Kuehnle ◽  
Stewart Edie ◽  
...  
Keyword(s):  
Species Richness ◽  
Range Size ◽  
Species Range ◽  
Latitudinal Gradients ◽  
Species Diversification ◽  
Marine Bivalves ◽  
The Tropics ◽  
Genus Expansion

Many marine and terrestrial clades show similar latitudinal gradients in species richness, but opposite gradients in range size—on land, ranges are the smallest in the tropics, whereas in the sea, ranges are the largest in the tropics. Therefore, richness gradients in marine and terrestrial systems do not arise from a shared latitudinal arrangement of species range sizes. Comparing terrestrial birds and marine bivalves, we find that gradients in range size are concordant at the level of genera. Here, both groups show a nested pattern in which narrow-ranging genera are confined to the tropics and broad-ranging genera extend across much of the gradient. We find that (i) genus range size and its variation with latitude is closely associated with per-genus species richness and (ii) broad-ranging genera contain more species both within and outside of the tropics when compared with tropical- or temperate-only genera. Within-genus species diversification thus promotes genus expansion to novel latitudes. Despite underlying differences in the species range-size gradients, species-rich genera are more likely to produce a descendant that extends its range relative to the ancestor's range. These results unify species richness gradients with those of genera, implying that birds and bivalves share similar latitudinal dynamics in net species diversification.

scholarly journals Common latitudinal gradients in functional richness and functional evenness across marine and terrestrial systems

2019 ◽  
Vol 286 (1908) ◽  
pp. 20190745 ◽  
Author(s):  
M. Schumm ◽  
S. M. Edie ◽  
K. S. Collins ◽  
V. Gómez-Bahamón ◽  
K. Supriya ◽  
...  
Keyword(s):  
Species Richness ◽  
Functional Groups ◽  
Functional Diversity ◽  
Skewed Distribution ◽  
Model Systems ◽  
Latitudinal Gradients ◽  
Ecological Specialization ◽  
Functional Richness ◽  
The Tropics ◽  
Functional Evenness

Functional diversity is an important aspect of biodiversity, but its relationship to species diversity in time and space is poorly understood. Here we compare spatial patterns of functional and taxonomic diversity across marine and terrestrial systems to identify commonalities in their respective ecological and evolutionary drivers. We placed species-level ecological traits into comparable multi-dimensional frameworks for two model systems, marine bivalves and terrestrial birds, and used global species-occurrence data to examine the distribution of functional diversity with latitude and longitude. In both systems, tropical faunas show high total functional richness (FR) but low functional evenness (FE) (i.e. the tropics contain a highly skewed distribution of species among functional groups). Functional groups that persist toward the poles become more uniform in species richness, such that FR declines and FE rises with latitude in both systems. Temperate assemblages are more functionally even than tropical assemblages subsampled to temperate levels of species richness, suggesting that high species richness in the tropics reflects a high degree of ecological specialization within a few functional groups and/or factors that favour high recent speciation or reduced extinction rates in those groups.

scholarly journals Differences in tropical vs. temperate diversity in arthropod predators provide insights into causes of latitudinal gradients of species diversity

2018 ◽  
Author(s):  
Kaïna Privet ◽  
Julien Petillon
Keyword(s):  
Species Richness ◽  
Temperate Forest ◽  
Diet Breadth ◽  
Latitudinal Gradients ◽  
Tropical Rainforests ◽  
Generalist Predators ◽  
Terrestrial Arthropods ◽  
Arthropod Predators ◽  
Tropical Diversity ◽  
The Tropics

AbstractHigh diversity in tropical compared to temperate regions has long intrigued ecologists. Terrestrial arthropods are among the most speciose orders in tropical rainforests. Previous studies show that arthropod herbivores account for much tropical diversity, yet differences in diversity of arthropod predators between tropical and temperate systems have not been quantified. Here, we present the first standardized tropical-temperate forest comparison of species richness and evenness for understory spiders, a dominant and mega-diverse taxa of generalist predators. Species richness was 13-82 times higher in tropical vs. temperate forests. Evenness was also higher with tropical assemblages having 12-55 times more common and 10-40 times more dominant species. By contrast, proportion of rare species were only up to two times greater than that of temperate measurements. These differences in diversity far surpass previous estimates, and exceed tropical-temperate difference for herbivorous taxa. Thus, the extreme diversity of arthropod predators is associated not only with the higher diversity of prey in tropical vs. temperate ecosystems, but probably also with increased diet breadth of understory spiders in the tropics. This work contradicts the widely accepted hypothesis that tropical diversity is associated with more specialization of predators.

scholarly journals Diversification, sympatry, and the emergence of mega-diverse tropical assemblages

2017 ◽  
Author(s):  
Jacob B. Socolar ◽  
Alexander C. Lees
Keyword(s):  
Species Richness ◽  
Species Coexistence ◽  
Sympatric Species ◽  
Latitudinal Gradients ◽  
Evolutionary Patterns ◽  
Multiple Timescales ◽  
Diversification Rates ◽  
Evolutionary Diversification ◽  
Extinction Rates ◽  
High Diversity

ABSTRACTGeographic gradients in species richness, including latitudinal gradients, can arise from geographic variation in any of three mechanisms: the geologic age of habitats, net rates of evolutionary diversification, or rates of sympatry among diversifying lineages. Here we show that variation in rates of sympatry is a dominant force structuring geographic richness gradients in birds. Species-rich sites contain disproportionately high numbers of recently diverged sympatric species but contain lineages with slower-than-average diversification rates. The positive sympatry-diversity relationship consistently overwhelms the negative diversification-diversity relationship, particularly among high-diversity sites (>250 species). These patterns repeat across biomes and continents with striking regularity, and remain consistent across multiple timescales, including the recent evolutionary past. Biogeographic and evolutionary patterns in birds are consistent with a role for ecological conditions in promoting species coexistence, which allows sister species to co-occur and potentially lowers extinction rates.

scholarly journals Richness and phylogenetic diversity are affected by space and time in the megadiverse Atlantic Forest of South America

2018 ◽  
Author(s):  
José Thales da Motta Portillo ◽  
Fausto Erritto Barbo ◽  
Josué Anderson Rêgo Azevedo ◽  
Ricardo Jannini Sawaya
Keyword(s):  
Species Richness ◽  
South America ◽  
Atlantic Forest ◽  
Phylogenetic Diversity ◽  
Latitudinal Gradient ◽  
Environmental Gradients ◽  
Negative Relationship ◽  
Latitudinal Gradients ◽  
Tropical Regions ◽  
The Tropics

Understanding variation of species richness along latitudinal gradients, with more species toward the tropics, represents a challenge for ecologists. Species richness also varies according to the available area, with more species in larger regions, with area and latitude posited as major drivers of richness variations. However, species richness does not fully capture the evolutionary history behind those patterns. Phylogenetic diversity can provide insights on the role of time and evolutionary drivers of environmental gradients. We analyzed here the latitudinal gradient of endemic snakes from the Atlantic Forest of South America, a megadiverse and highly threatened portion of the Neotropics. We assessed the effect of area and average clade age on species richness and phylogenetic diversity, testing whether species richness and phylogenetic diversity increase with area availability and in lower latitudes. We found that area can predict species richness, but not phylogenetic diversity. Brazilian southeastern mountain ranges include larger patches of Atlantic Forest and the highest richness levels, but generally harboring snakes from relatively recent clades (neoendemics). There is a negative relationship between species richness and average clade age along the latitudinal gradient, with older clades found mainly in northern portions, increasing phylogenetic diversity at lower latitudes. Different dimensions of diversity, species richness and phylogenetic diversity, are thus affected in different ways by area and time for speciation in the Atlantic Forest, and this may be a trend in highly diverse tropical regions.

scholarly journals Richness and phylogenetic diversity are affected by space and time in the megadiverse Atlantic Forest of South America

2018 ◽  
Author(s):  
José Thales da Motta Portillo ◽  
Fausto Erritto Barbo ◽  
Josué Anderson Rêgo Azevedo ◽  
Ricardo Jannini Sawaya
Keyword(s):  
Species Richness ◽  
South America ◽  
Atlantic Forest ◽  
Phylogenetic Diversity ◽  
Latitudinal Gradient ◽  
Environmental Gradients ◽  
Negative Relationship ◽  
Latitudinal Gradients ◽  
Tropical Regions ◽  
The Tropics

Understanding variation of species richness along latitudinal gradients, with more species toward the tropics, represents a challenge for ecologists. Species richness also varies according to the available area, with more species in larger regions, with area and latitude posited as major drivers of richness variations. However, species richness does not fully capture the evolutionary history behind those patterns. Phylogenetic diversity can provide insights on the role of time and evolutionary drivers of environmental gradients. We analyzed here the latitudinal gradient of endemic snakes from the Atlantic Forest of South America, a megadiverse and highly threatened portion of the Neotropics. We assessed the effect of area and average clade age on species richness and phylogenetic diversity, testing whether species richness and phylogenetic diversity increase with area availability and in lower latitudes. We found that area can predict species richness, but not phylogenetic diversity. Brazilian southeastern mountain ranges include larger patches of Atlantic Forest and the highest richness levels, but generally harboring snakes from relatively recent clades (neoendemics). There is a negative relationship between species richness and average clade age along the latitudinal gradient, with older clades found mainly in northern portions, increasing phylogenetic diversity at lower latitudes. Different dimensions of diversity, species richness and phylogenetic diversity, are thus affected in different ways by area and time for speciation in the Atlantic Forest, and this may be a trend in highly diverse tropical regions.

scholarly journals Exploring diversification drivers in golden orbweavers

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Eva Turk ◽  
Simona Kralj-Fišer ◽  
Matjaž Kuntner
Keyword(s):  
Environmental Factors ◽  
Sexual Size Dimorphism ◽  
Male Body ◽  
Diversification Rates ◽  
Size Dimorphism ◽  
Extinction Rates ◽  
Intermediate Phenotypes ◽  
Dispersal Propensity ◽  
The Tropics ◽  
Class Models

AbstractHeterogeneity in species diversity is driven by the dynamics of speciation and extinction, potentially influenced by organismal and environmental factors. Here, we explore macroevolutionary trends on a phylogeny of golden orbweavers (spider family Nephilidae). Our initial inference detects heterogeneity in speciation and extinction, with accelerated extinction rates in the extremely sexually size dimorphic Nephila and accelerated speciation in Herennia, a lineage defined by highly derived, arboricolous webs, and pronounced island endemism. We evaluate potential drivers of this heterogeneity that relate to organisms and their environment. Primarily, we test two continuous organismal factors for correlation with diversification in nephilids: phenotypic extremeness (female and male body length, and sexual size dimorphism as their ratio) and dispersal propensity (through range sizes as a proxy). We predict a bell-shaped relationship between factor values and speciation, with intermediate phenotypes exhibiting highest diversification rates. Analyses using SSE-class models fail to support our two predictions, suggesting that phenotypic extremeness and dispersal propensity cannot explain patterns of nephilid diversification. Furthermore, two environmental factors (tropical versus subtropical and island versus continental species distribution) indicate only marginal support for higher speciation in the tropics. Although our results may be affected by methodological limitations imposed by a relatively small phylogeny, it seems that the tested organismal and environmental factors play little to no role in nephilid diversification. In the phylogeny of golden orbweavers, the recent hypothesis of universal diversification dynamics may be the simplest explanation of macroevolutionary patterns.

Sign in / Sign up

Export Citation Format

Share Document