Environmental heterogeneity dynamics drive plant diversity on oceanic islands

Barbosa, Martha Paola Barajas; Weigelt, Patrick; Borregaard, Michael K.; Keppel, Gunnar; Kreft, Holger

doi:10.1111/jbi.13925

Cited by 41 publications

(47 citation statements)

References 77 publications

(102 reference statements)

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“…Species richness for all taxonomic groups in this study was predicted by the GDM (ATT 2 independently for 10 groups and ATT 2 + Isolation + Habitat Diversity for 11 groups; Table S1.4), even though topographic complexity (TC) itself did not follow the hump‐shaped curve as previously predicted. Our findings of ATT 2 as a significant predictor for plants, snails and invertebrates aligns with previous studies (Barajas‐Barbosa et al, 2020; Cameron et al, 2013; Cardoso et al, 2010; Steinbauer et al, 2013; Whittaker et al, 2008), and we also find a similar relationship for higher dispersing organisms such as birds. Therefore, our study largely supports that the hump‐shaped relationship of island age can predict species richness (Whittaker et al, 2008).…”

Section: Discussionsupporting

confidence: 92%

“…For plants, we found that the TC indices RE and SE predict species richness in NE_P and improve multiple models in both NE_P and SIE_P. This directly aligns with Barajas‐Barbosa et al’s (2020) findings as four out of five measures of elevation they tested (including RE and SE) increased diversity in both NE and SIE plants (the Galápagos archipelago was included in their data set of 135 volcanic archipelagos).…”

Section: Discussionsupporting

confidence: 88%

“…Of the variables tested, habitat diversity had the greatest impact by increasing the explanatory power of the GDM models. This finding underscores the importance of habitat heterogeneity in promoting richness across taxonomic groups (Barajas‐Barbosa et al, 2020; Stein et al, 2014; Stein & Kreft, 2015). It is also noteworthy that species richness in fewer taxonomic groups was independently predicted by topographic complexity ( N = 5) and island isolation ( N = 4) compared to habitat diversity (all 12 groups).…”

Section: Discussionsupporting

confidence: 60%

“…However, despite these correlations, no models produced identical results across taxonomic groups, illustrating the taxon‐specific patterns in response to different aspects of TC. Similarly, Barajas‐Barbosa et al (2020) retained different EH variables (e.g. elevation and temperature heterogeneity) that were revealed to be collinear in their analyses to capture different aspects of EH that might have slightly different effects on species richness.…”

Section: Discussionmentioning

confidence: 99%

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Effect of topographic complexity on species richness in the Galápagos Islands

Roell

Phillips

Parent

2021

Journal of Biogeography

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Aim The accumulation of species through time has been proposed to have a hump‐shaped relationship on volcanic islands (highest species richness during intermediate stages of an island's lifespan). Change in topographic complexity (TC) of islands over time is assumed to follow the same relationship. However, TC can be measured in different ways and may not have the same impact across taxonomic groups. Here, we quantify TC across the Galápagos Islands and test the assumption that TC follows a predictable trajectory with island age. Subsequently, we ask whether including TC improves statistical models seeking to explain variation in species richness across islands. Location Galápagos Archipelago, Ecuador. Taxon Native and endemic terrestrial animals and plants. Methods For each island, we generated eight TC indices from a 30‐m resolution digital elevation model. We tested for a relationship between each index and island age, and whether it significantly contributes to observed variation in species richness, using 11 different models for 12 taxonomic groups across the Galápagos Islands. Results Four TC indices were significantly negatively correlated with either island age or ontogenetic age and only one index followed the hump‐shaped relationship with age. No index consistently contributed to the variation in species richness for all taxonomic groups. However, for all 12 taxonomic groups, incorporating at least one TC index in modelling species richness improved one or more models. The most common TC index improving models was standard deviation of slope, although each index improved at least five models across all taxa. Different factors predicted taxon‐specific richness, and habitat diversity was significant for all taxa. Main conclusions Topographic complexity is an important component influencing species richness, but its impact likely differs among taxonomic groups and different scales. Therefore, future studies should incorporate broad, multi‐dimensional measures of TC to understand the biological importance of TC.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionsupporting

confidence: 88%

Section: Discussionsupporting

confidence: 60%

Section: Discussionmentioning

confidence: 99%

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Effect of topographic complexity on species richness in the Galápagos Islands

Roell

Phillips

Parent

2021

Journal of Biogeography

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“…The generality of the robustness pipeline developed here allows for other studies on the robustness of other models under complex generating processes. Alternative hypotheses for island changes are changing isolation, topographical complexity, or evolution of environmental heterogeneity as new islands undergo succession (Massol et al, 2017;Barajas-Barbosa et al, 2020).…”

Section: Robustness Studies In Phylogeneticsmentioning

confidence: 99%

The robustness of a simple dynamic model of island biodiversity to geological and eustatic change

Neves

Lambert

Valente

et al. 2021

Preprint

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Aim: Biodiversity on islands is affected by various geo-physical processes and sea-level fluctuations. Oceanic islands (never connected to a landmass) are initially vacant with diversity accumulating via colonisation and speciation, followed by a decline as islands shrink. Continental islands have species upon formation (when disconnected from the mainland) and may have transient land-bridge connections. Theoretical predictions for the effects of these geo-processes on rates of colonisation, speciation and extinction have been proposed, but methods of phylogenetic inference assume only oceanic island scenarios without accounting for island ontogeny, sea-level changes or past landmass connections. Here, we analyse to what extent ignoring geodynamics affects the inference performance of a phylogenetic island model, DAISIE, when confronted with simulated data that violate its assumptions. Location: Simulation of oceanic and continental islands. Methods: We extend the DAISIE simulation model to include: area-dependent rates of colonisation and diversification associated with island ontogeny and sea-level fluctuations, and continental islands with biota present upon separation from the mainland, and shifts in rates to mimic temporary land-bridges. We quantify the error made when geo-processes are not accounted for by applying DAISIE's inference method to geodynamic simulations. Results: We find that the robustness of the model to dynamic island area is high (error is small) for oceanic islands and for continental islands that have been separated for a long time, suggesting that, for these island types, it is possible to obtain reliable results when ignoring geodynamics. However, for continental islands that have been recently or frequently connected, robustness of DAISIE is low, and inference results should not be trusted. Main conclusions: This study highlights that under a large proportion of island biogeographic geo-scenarios (oceanic islands and ancient continental fragments) a simple phylogenetic model ignoring geodynamics is empirically applicable and informative. However, recent connection to the continent cannot be ignored, requiring development of a new inference model.

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A niche‐based theory of island biogeography

Beaugrand,

Kléparski,

Luczak

et al. 2024

Ecology and Evolution

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The equilibrium theory of island biogeography (ETIB) is a widely applied dynamic theory proposed in the 1960s to explain why islands have coherent differences in species richness. The development of the ETIB was temporarily challenged in the 1970s by the alternative static theory of ecological impoverishment (TEI). The TEI suggests that the number of species on an island is determined by its number of habitats or niches but, with no clear evidence relating species richness to the number of niches however, the TEI has been almost dismissed as a theory in favour of the original ETIB. Here, we show that the number of climatic niches on islands is an important predictor of the species richness of plants, herpetofauna and land birds. We therefore propose a model called the niche‐based theory of island biogeography (NTIB), based on the MacroEcological Theory on the Arrangement of Life (METAL), which successfully integrates the number of niches sensu Hutchinson into ETIB. To account for greater species turnover at the beginning of colonisation, we include higher initial extinction rates. When we test our NTIB for resident land birds in the Krakatau Islands, it reveals a good correspondence with observed species richness, immigration and extinction rates. Provided the environmental regime remains unchanged, we estimate that the current species richness at equilibrium is ~45 species (range between 38.39 and 61.51). Our NTIB provides better prediction because it counts for changes in species richness with latitude, which is not considered in any theory of island biogeography.

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Environmental heterogeneity dynamics drive plant diversity on oceanic islands

Abstract: This is an open access article under the terms of the Creat ive Commo ns Attri bution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Cited by 41 publications

References 77 publications

Effect of topographic complexity on species richness in the Galápagos Islands

Effect of topographic complexity on species richness in the Galápagos Islands

The robustness of a simple dynamic model of island biodiversity to geological and eustatic change

A niche‐based theory of island biogeography

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