Truncated bimodal latitudinal diversity gradient in early Paleozoic phytoplankton

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.

Download Full-text

The contribution of global mountains to the latitudinal diversity gradient

10.1101/2020.07.04.188227 ◽

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.

Download Full-text

Geomorphological approach to the river runoff evaluation in the geological past (рaper 5. Comparison of the estimates by different methods)

Geomorphology RAS ◽

10.31857/s0435-42812019166-79 ◽

2019 ◽

pp. 66-79

Author(s):

A. Yu. Sidorchuk ◽

A. V. Panin ◽

O. K. Borisova

Keyword(s):

Water Resources ◽

Water Flow ◽

Climate Changes ◽

Annual Runoff ◽

Fossil Flora ◽

Average Error ◽

Flow Estimation ◽

The Past ◽

Geological Past

The estimates of water flow in the paleorivers with known paleochannel morphometry was compared with basic hydrological and climatic indicators found by paleogeographic analogy in the regions-analogues, determined by fossil flora analysis from the Holocene (from the present to 10 thousand years ago), the Late Valday (17–18 thousand years ago) and before the Eemian (~140 thousand years ago) deposits. Comparison of annual runoff depth obtained by regime equations and equations of hydraulics and taken from the hydrological maps in the regions-analogues, showed quite satisfactory compliance. Relative error of comparison for the different objects is in the range of ±11–23%, which does not exceed the average error of water flow estimation by each of these techniques separately. However, the error of ±20% is significant and geomorphological approaches can be applied only for the cases of sufficient changes in the water flow of ancient rivers (twice or more) and for long-term periods. Nevertheless, the use of geomorphological approaches and the method of paleogeographic analogy is now one of the main ways to reconstruct water resources in the past and to construct water resources scenarios for possible future climate changes.

Download Full-text

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

10.1101/668079 ◽

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.

Download Full-text

Unprecedented ichneumonid parasitoid wasp diversity in tropical forests

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2012.1664 ◽

2012 ◽

Vol 279 (1748) ◽

pp. 4694-4698 ◽

Cited By ~ 46

Author(s):

Anu Veijalainen ◽

Niklas Wahlberg ◽

Gavin R. Broad ◽

Terry L. Erwin ◽

John T. Longino ◽

...

Keyword(s):

Species Richness ◽

Dna Analysis ◽

Morphological Characteristics ◽

Parasitoid Wasp ◽

Primary Data ◽

Sampling Effort ◽

Species Accumulation Curves ◽

Additional Species ◽

Diversity Gradient ◽

Richness Patterns

The megadiverse parasitoid wasp family Ichneumonidae (Hymenoptera) is classically considered an exception to the extensively studied latitudinal diversity gradient: the majority of ichneumonid species are described from temperate regions. The gradient has been hypothesized to be dependent on the biology of the wasps, but recently questions of sampling and description biases have been raised. Here, we show with primary data that the species richness of Ichneumonidae is markedly underestimated in tropical areas and that latitudinal diversity patterns in the family remain uncharacterized. We discovered a startling 177 likely undescribed orthocentrine species with relatively low sampling effort in the forests of Central America and Amazonian Ecuador, over three times the previously known orthocentrine diversity in the world's tropics. Species accumulation curves reveal that we are just beginning to unveil the true extent of tropical orthocentrine diversity. We also found evidence for cryptic species; our DNA analysis revealed additional species not easily distinguishable using morphological characteristics. The difficulty in establishing species richness patterns of Ichneumonidae probably follows from the relative lack of taxonomic expertise and the low density of ichneumonid species throughout the landscape.

Download Full-text

The latitudinal diversity gradient and interspecific competition: no global relationship between lizard dietary niche breadth and species richness

Global Ecology and Biogeography ◽

10.1111/geb.12560 ◽

2017 ◽

Vol 26 (5) ◽

pp. 563-572 ◽

Cited By ~ 12

Author(s):

Alison Gainsbury ◽

Shai Meiri

Keyword(s):

Species Richness ◽

Interspecific Competition ◽

Niche Breadth ◽

Latitudinal Diversity Gradient ◽

Diversity Gradient ◽

Dietary Niche

Download Full-text

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

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2021.0545 ◽

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.

Download Full-text

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

10.22541/au.163705573.37659202/v1 ◽

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.

Download Full-text