scholarly journals Evolutionary time best explains the latitudinal diversity gradient of living freshwater fish diversity

2019 ◽  
Author(s):  
Elizabeth Christina Miller ◽  
Cristian Román-Palacios
Keyword(s):  
Species Richness ◽  
Freshwater Fish ◽  
Surface Area ◽  
Explanatory Power ◽  
Additive Models ◽  
Fish Diversity ◽  
Diversification Rates ◽  
Latitudinal Diversity Gradient ◽  
Diversity Gradient ◽  
Basin Surface

AbstractAimThe evolutionary causes of the latitudinal diversity gradient are debated. Hypotheses have ultimately invoked either faster rates of diversification in the tropics, or more time for diversification due to the tropical origins of higher taxa. Here we perform the first test of the diversification rate and time hypotheses in freshwater ray-finned fishes, a group comprising nearly a quarter of all living vertebrates.LocationGlobal.Time period368–0 mya.Major taxa studiedExtant freshwater ray-finned fishes.MethodsUsing a mega-phylogeny of actinopterygian fishes and a global database of occurrence records, we estimated net diversification rates, the number of colonizations and regional colonization times of co-occurring species in freshwater drainage basins. We used Generalized Additive Models to test whether these factors were related to latitude. We then compared the influence of diversification rates, colonization numbers, colonization times and surface area on species richness, and how these factors are related to each other.ResultsWhile both diversification rates and time were related to richness, time had greater explanatory power and was more strongly related to latitude than diversification rates. Other factors (basin surface area, number of colonizations) also helped explain richness but were unrelated to latitude. The world’s most diverse freshwater basins (Amazon, Congo rivers) were dominated by lineages with Mesozoic origins. The temperate groups dominant today arrived near the K-Pg boundary, leaving comparatively less time to build richness. Diversification rates and colonization times were inversely related: recently colonized basins had the fastest rates, while ancient species-rich faunas had slower rates.Main conclusionsWe concluded that time is the lead driver of latitudinal richness disparities in freshwater fish faunas. We suggest that the most likely path to building very high species richness is through diversification over long periods of time, rather than diversifying quickly.

scholarly journals The contribution of global mountains to the latitudinal diversity gradient

2020 ◽  
Author(s):  
Elkin A. Tenorio ◽  
Paola Montoya ◽  
Natalia Norden ◽  
Susana Rodríguez-Buriticá ◽  
Beatriz Salgado-Negret ◽  
...  
Keyword(s):  
Species Richness ◽  
Unit Area ◽  
Species Turnover ◽  
Geographical Information ◽  
Mountain Ranges ◽  
Terrestrial Vertebrates ◽  
Latitudinal Diversity Gradient ◽  
Diversity Gradient ◽  
Diversity Gradients ◽  
Time And Energy

AbstractThe latitudinal diversity gradient (LDG) is widely attributed to be the result of factors such as time, area, and energy. Although these factors explain most of the variation in lowlands, they fail in mountainous systems, which are biodiversity hotspots that may contribute meaningfully to the strength of the pattern following different evolutionary pathways. However, because lowlands cover the largest portion of the total land, they may have overshadowed the contribution of mountains to the LDG, but no study has addressed this issue in previous macroecological analyses. Here, we propose that the LDG shows a stronger trend in mountain ranges due to their high species turnover, in spite of covering less than one third of the Earth’s land. Using the geographical information for ∼22000 species of terrestrial vertebrates, we show that worldwide mountains harbor the 40% of the global diversity, and when taking into account the area effect, we quantified that mountains harbor close to double the species inhabiting lowlands per unit area. Moreover, when we evaluated the LDG after accounting for area size, we found that species richness increased faster towards the Equator and was better predicted by latitude in mountains than in lowlands. Our findings challenge previously well-supported hypotheses that predict that those regions with greater area, time and energy accumulate more species richness, since mountains are geologically younger, exhibit less energy, and cover smaller areas than lowlands. Hence, mountains represent a paradox, which invites to reevaluate hypotheses regarding macroecological and evolutionary processes driving species diversity gradients.

scholarly journals Ecological causes of uneven speciation and species richness in mammals

2019 ◽  
Author(s):  
Nathan S. Upham ◽  
Jacob A. Esselstyn ◽  
Walter Jetz
Keyword(s):  
Species Richness ◽  
Species Turnover ◽  
Rate Variation ◽  
Ecological Traits ◽  
Ecological Opportunity ◽  
Diversification Rates ◽  
Speciation Rate ◽  
Diversity Gradient ◽  
Speciation Rates

ABSTRACTBiodiversity is distributed unevenly from the poles to the equator, and among branches of the tree of life, yet how those enigmatic patterns are related is unclear. We investigated global speciation-rate variation across crown Mammalia using a novel time-scaled phylogeny (N=5,911 species, ~70% with DNA), finding that trait- and latitude-associated speciation has caused uneven species richness among groups. We identify 24 branch-specific shifts in net diversification rates linked to ecological traits. Using time-slices to define clades, we show that speciation rates are a stronger predictor of clade richness than age. Speciation is slower in tropical than extra-tropical lineages, but only at the level of clades not species tips, consistent with fossil evidence that the latitudinal diversity gradient may be a relatively young phenomenon in mammals. In contrast, species tip rates are fastest in mammals that are low dispersal or diurnal, consistent with models of ephemeral speciation and ecological opportunity, respectively. These findings juxtapose nested levels of diversification, suggesting a central role of species turnover gradients in generating uneven patterns of modern biodiversity.

The metabolic theory of ecology convincingly explains the latitudinal diversity gradient of Neotropical freshwater fish

Ecology ◽  
2014 ◽  
Vol 95 (2) ◽  
pp. 553-562 ◽  
Author(s):  
Dayani Bailly ◽  
Fernanda A. S. Cassemiro ◽  
Carlos S. Agostinho ◽  
Elineide E. Marques ◽  
Angelo A. Agostinho
Keyword(s):  
Freshwater Fish ◽  
Metabolic Theory ◽  
Metabolic Theory Of Ecology ◽  
Latitudinal Diversity Gradient ◽  
Diversity Gradient

scholarly journals Truncated bimodal latitudinal diversity gradient in early Paleozoic phytoplankton

2021 ◽  
Vol 7 (15) ◽  
pp. eabd6709
Author(s):  
Axelle Zacaï ◽  
Claude Monnet ◽  
Alexandre Pohl ◽  
Grégory Beaugrand ◽  
Gary Mullins ◽  
...  
Keyword(s):  
Species Richness ◽  
Climate Changes ◽  
Sea Surface ◽  
Marine Phytoplankton ◽  
Sampling Effort ◽  
Early Paleozoic ◽  
Latitudinal Diversity Gradient ◽  
Diversity Gradient ◽  
Geological Past

The latitudinal diversity gradient (LDG)—the decline in species richness from the equator to the poles—is classically considered as the most pervasive macroecological pattern on Earth, but the timing of its establishment, its ubiquity in the geological past, and explanatory mechanisms remain uncertain. By combining empirical and modeling approaches, we show that the first representatives of marine phytoplankton exhibited an LDG from the beginning of the Cambrian, when most major phyla appeared. However, this LDG showed a single peak of diversity centered on the Southern Hemisphere, in contrast to the equatorial peak classically observed for most modern taxa. We find that this LDG most likely corresponds to a truncated bimodal gradient, which probably results from an uneven sediment preservation, smaller sampling effort, and/or lower initial diversity in the Northern Hemisphere. Variation of the documented LDG through time resulted primarily from fluctuations in annual sea-surface temperature and long-term climate changes.

scholarly journals Can net diversification rates account for spatial patterns of species richness?

2017 ◽  
Author(s):  
Camilo Sanín ◽  
Iván Jiménez ◽  
Jon Fjeldså ◽  
Carsten Rahbek ◽  
Carlos Daniel Cadena
Keyword(s):  
Species Richness ◽  
Spatial Variation ◽  
Spatial Patterns ◽  
Explanatory Power ◽  
Large Family ◽  
Diversification Rate ◽  
Diversification Rates ◽  
Grain Sizes ◽  
Time Period ◽  
Richness Patterns

ABSTRACTThe diversification rate hypothesis (DRH) proposes that spatial patterns of species richness result from spatial variation in net diversification rates. We developed an approach using a time-calibrated phylogeny and distributional data to estimate the maximum explanatory power of the DRH, over a given time period, to current species richness in an area. We used this approach to study species richness patterns of a large family of suboscine birds across South America. The maximum explanatory power of the DRH increased with the duration of the time period considered and grain size; it ranged from 13 – 37 fold local increases in species richness for T = 33 Ma to less than 2-fold increases for T ≤ 10 Ma. For large grain sizes (≤ 8° × 8°) diversification rate over the last 10 Ma could account for all the spatial variance in species richness, but for smaller grain sizes commonly used in biogeographical studies (1° × 1°), it could only explain < 16% of this variance. Thus, diversification since the Late Miocene, often thought to be a major determinant of Neotropical diversity, had a limited imprint on spatial richness patterns at small grain sizes. Further application of our approach will help determine the role of the DRH in explaining current spatial patterns of species richness.Note to readersThis manuscript has been seen by a few researchers, some of whom suggested that before publishing our work in a peer-reviewed journal we should conduct simulations to demonstrate that our methods properly estimate the contribution of variance in diversification rates to spatial variation in species richness. Although we believe that our approach derives logically from theory and statistics and is therefore valid, we understand that it is rather unique and see why some readers would think that an independent validation is necessary. Unable to complete such validation in the near future, however, we decided to make this manuscript available as a preprint to share our ideas and hopefully stimulate discussion on what we believe is a most interesting topic. We also hope to receive feedback that may enable us to improve our work for publication in a journal at a later date.

scholarly journals Out of the extratropics: the evolution of the latitudinal diversity gradient of Cenozoic marine plankton

2021 ◽  
Vol 288 (1950) ◽  
Author(s):  
Nussaïbah B. Raja ◽  
Wolfgang Kiessling
Keyword(s):  
Species Richness ◽  
Opposite Direction ◽  
Large Scale ◽  
Climatic Changes ◽  
Marine Plankton ◽  
Latitudinal Diversity Gradient ◽  
Diversity Gradient ◽  
Cenozoic Era ◽  
The Tropics ◽  
Early Cenozoic

Many ecological and evolutionary hypotheses have been proposed to explain the latitudinal diversity gradient, i.e. the increase in species richness from the poles to the tropics. Among the evolutionary hypotheses, the ‘out of the tropics’ (OTT) hypothesis has received considerable attention. The OTT posits that the tropics are both a cradle and source of biodiversity for extratropical regions. To test the generality of the OTT hypothesis, we explored the spatial biodiversity dynamics of unicellular marine plankton over the Cenozoic era (the last 66 Myr). We find large-scale climatic changes during the Cenozoic shaped the diversification and dispersal of marine plankton. Origination was generally more likely in the extratropics and net dispersal was towards the tropics rather than in the opposite direction, especially during the warmer climates of the early Cenozoic. Although migration proportions varied among major plankton groups and climate phases, we provide evidence that the extratropics were a source of tropical microplankton biodiversity over the last 66 Myr.

scholarly journals Yes, a non‐random distribution, but why do dragonflies and damselflies not follow latitudinal gradient rules?

2021 ◽  
Author(s):  
Maya Rocha ◽  
Freddy Palacino ◽  
Pilar Rodríguez ◽  
Alex Córdoba-Aguilar
Keyword(s):  
Species Richness ◽  
Community Assembly ◽  
Latitudinal Gradient ◽  
Environmental Filtering ◽  
Phylogenetic Structure ◽  
Latitudinal Diversity Gradient ◽  
Diversity Gradient ◽  
Historical Processes ◽  
Underlying Mechanisms ◽  
Different Origins

1. Latitudinal diversity gradient (LDG) is the increase in species richness towards the equator and is one of the most consistent patterns in biogeography, where current and historical processes contribute to shape the pattern. 2. Despite that LDG patterns have been described for some insects, the underlying mechanisms associated with community assembly and diversification along modern latitudinal diversity gradient pattern remain unknowledge for many groups. 3. Odonata is an old order of insects that originated during the Carboniferous and has diversified through different eras. Here, we defined co-occurrence based on the presence in ecoregions and 1°×1° grid cells of Odonata species in North America NA, to address their species richness, phylogenetic structure, and species diversification rate along the latitudinal gradient. 4. For the whole order, we found the highest species richness at mid-latitudes, while phylogenetic diversity showed a linear positive pattern along the gradient. Our results showed dragonfly assemblages were clustered along all the gradient, suggesting that environmental filtering sorted the assemblages. Whereas damselfly species assemblages were clustered at mid-latitude and overdispersed into both extremes of gradient, probably community assembly is driving by thermal gradients at mid-latitude, by competitive exclusion at south extreme, and by different origins of the biota at the boreal zone. Our results show that apparently most ancestral lineages of Odonata inhabit tropical zones, where diversified and dispersed to the temperate region, although likely also have been diversified into regions of NA, which might be linked with the highest species richness at mid-latitude for both suborders.

Exploring the origin of the latitudinal diversity gradient: Contrasting the sister fern generaPhegopterisandPseudophegopteris

2012 ◽  
pp. n/a-n/a
Author(s):  
Harald SCHNEIDER ◽  
Li-Juan HE ◽  
Jeannine MARQUARDT ◽  
Li WANG ◽  
Jochen HEINRICHS ◽  
...  
Keyword(s):  
Latitudinal Diversity Gradient ◽  
Diversity Gradient
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