How ancient forest fragmentation and riparian connectivity generate high levels of genetic diversity in a microendemic Malagasy tree

Salmona, Jordi; Dresen, Axel; Ranaivoson, Anicet E; Manzi, Sophie; Pors, Barbara Le; Hong‐Wa, Cynthia; Razanatsoa, Jacqueline; Andriaholinirina, Nicole; Rasoloharijaona, Solofonirina; Vavitsara, Marie-Elodie; Besnard, Guillaume

doi:10.1111/mec.16759

Cited by 7 publications

(8 citation statements)

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“…Additionally, we investigated patterns of genetic variance with a principal component analysis (PCA) of allele frequencies, with a DAPC (considering sampling regions as groups), and using the SnapClust clustering approach [47] for K = 1−15. To assess how the geographical distance alone explains the genetic diversity [48,49], we investigated individual- and population-based patterns of isolation by distance (IBD) using Mantel tests [50], and assessed which genetic distance metric and spatial scale best fitted the data [51,52]. To assess how dispersal is distributed geographically, we used Mantel correlograms [53,54].…”

Section: Methodsmentioning

confidence: 99%

The antique genetic plight of the Mediterranean monk seal ( Monachus monachus )

et al. 2022

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Disentangling the impact of Late Quaternary climate change from human activities can have crucial implications on the conservation of endangered species. We investigated the population genetics and demography of the Mediterranean monk seal ( Monachus monachus ), one of the world's most endangered marine mammals, through an unprecedented dataset encompassing historical (extinct) and extant populations from the eastern North Atlantic to the entire Mediterranean Basin. We show that Cabo Blanco (Western Sahara/Mauritania), Madeira, Western Mediterranean (historical range) and Eastern Mediterranean regions segregate into four populations. This structure is probably the consequence of recent drift, combined with long-term isolation by distance ( R 2 = 0.7), resulting from prevailing short-distance (less than 500 km) and infrequent long-distance dispersal (less than 1500 km). All populations (Madeira especially), show high levels of inbreeding and low levels of genetic diversity, seemingly declining since historical time, but surprisingly not being impacted by the 1997 massive die-off in Cabo Blanco. Approximate Bayesian Computation analyses support scenarios combining local extinctions and a major effective population size decline in all populations during Antiquity. Our results suggest that the early densification of human populations around the Mediterranean Basin coupled with the development of seafaring techniques were the main drivers of the decline of Mediterranean monk seals.

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Section: Methodsmentioning

confidence: 99%

The antique genetic plight of the Mediterranean monk seal ( Monachus monachus )

et al. 2022

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“…The spread of open grassy systems in Madagascar and the radiation of C4 grass lineages were mirrored in the spread and niche adaptation of savanna woody species about the same time in Madagascar (Choo et al, 2020; Salmona et al, 2020, 2021; Veranso‐Libalah et al, 2018). In addition to the role of fire, we know from paleontological studies elsewhere that large mammalian browsers were important in the spread of open, grassy systems during the Miocene (Janis et al, 2000).…”

Section: Evolutionary History Of the Development And Spread Of Open G...mentioning

confidence: 99%

“…This process fostered genetic divergence among isolated populations, eventually leading to genetic divergence and allopatric speciation. Those published studies consistent with this hypothesis include the following: (1) the genetic structure of widespread, endemic bat species Macronycteris commersoni (Rakotoarivelo et al, 2019); (2) several studies of cryptic variation in several mouse lemur species populations (Poelstra et al, 2021; Tiley et al, 2022; Sgarlata et al, 2018, and of course Yoder et al, 2016); (3) micro‐endemism in 26 new species of microhylid frogs (Rakotoarison et al, 2017); (4) bird species in the genus Newtonia (Family Vangidae) (Younger et al, 2018); (5) tenrec species (Everson et al, 2020); (6) Salmona et al (2017) on two species of lemurs; (7) dwarf lemurs (Williams et al, 2020); (8) noctuid moths in the Central Highlands (Wiorek et al, 2021); (9) Quéméré et al (2012 on the golden‐crowned sifaka in northern Madagascar; and (10) Salmona et al (2021) on the diversification of some 60 forest and savanna species of Noronhia across Madagascar. It is noteworthy that mosaiced landscapes may not only have promoted evolution of various faunal clades but also may promote higher landscape biodiversity today (cf.…”

Section: Evolutionary History Of the Development And Spread Of Open G...mentioning

confidence: 99%

“…There is growing evidence that well‐functioning and biodiverse grassy ecosystems are under threat in Madagascar. See Salmona et al (2021), Waeber et al (2015), Virah‐Sawmy (2009), and Bardgett et al (2021) on conservation issues related to grassy systems including open woodlands of Madagascar. See also Rakotoarimanana et al (2001); Alvarado, Buisson, Rabarison, Rajeriarison, Birkinshaw, Lowry, and Morellato (2014b); Bloesch et al (2019); and Pareliussen (2004) and Pareliussen et al (2006) on how to manage these ecosystems sustainably with varying fire regimes.…”

Section: Conservation and Management Of Open Grassy Systems In Madaga...mentioning

confidence: 99%

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The grassy ecosystems of Madagascar in context: Ecology, evolution, and conservation

Silander,

Bond,

Ratsirarson

2023

Plants People Planet

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Societal Impact StatementMadagascar is famous for its unique forests and their fauna. Most of the island is covered by flammable grassy ecosystems long considered to be of human origin and threatening the remaining forests. Yet new studies show that many plants and animals of the grassy systems are unique to Madagascar and restricted to these open habitats. Open grassy ecosystems have markedly different management requirements from forests and bring different contributions to society. We argue that the grassy ecosystems can benefit Madagascar if understood and managed wisely using expanded knowledge bases that also include collaboration with locals.SummaryUntil recently, nearly all research and interests in Madagascar focused on forested habitats. To help place Madagascar's grassy ecosystems in context, we provide a summary of the origin, development, and evolution of open tropical, C4 grassy ecosystems elsewhere, especially those from Africa; we summarize similarities and differences with the distribution of C3 and C4 grasses in the Malagasy landscape, their plant traits, and inferences on the evolutionary legacy of grasses. We also discuss the animal communities that use and have coevolved in these grassy systems; to help resolve controversies over the pre‐settlement extent of grassy ecosystems, we suggest a variety of complementary geochemical, palaeobotanical, and molecular genetic tools that have been effectively used elsewhere to untangle forest/grassy ecosystem mosaics and the ecological and evolutionary processes that influence them. Many of these tools can and should be employed in Madagascar to fully understand the spatio‐temporal dynamics of open, grassy, and closed forest systems across the island; as regards conservation, we discuss the ecosystem services provided by grassy systems, which are too often ignored in general, not only as a biome, vis‐à‐vis forests, but also for their global importance as a carbon sink and role they play in water management and providing goods to local villagers. We conclude by outlining the necessary research to better manage open ecosystems across Madagascar without threatening endangered forest ecosystems.

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“…), and both isolation by distance and isolation by environment were inferred to affect genetic differentiation between orchid populations (Andriamihaja et al, 2021). Current forest cover has also been shown to be important for driving genetic diversity and genetic structure of endemic plants in Madagascar (Salmona et al, 2022). Finally, besides frugivores and the abiotic environment, humans have been a major determinant of present-day genetic diversity and genetic structure of plants (Arredondo et al, 2018;Smith et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Genomic signatures of past megafrugivore-mediated dispersal in Malagasy palms

Méndez

Barratt

Durka

et al. 2023

Preprint

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1. Seed dispersal is a key process in the generation and maintenance of genetic diversity and genetic differentiation of plant populations in tropical ecosystems. During the Last Quaternary, most seed-dispersing megafauna was lost globally, but whether this has caused dispersal limitation, loss of genetic diversity, and increased genetic differentiation between plant populations with large, megafaunal fruits (i.e., > 4 cm - megafruits) remains unclear. 2. Here, we assessed whether megafrugivore extinctions in Madagascar (e.g., giant lemurs, elephant birds) have affected the genetic diversity and genetic differentiation of four animal-dispersed Malagasy palm (Arecaceae) species with large (Borassus madagascariensis), medium-sized (Hyphaene coriacea, Bismarckia nobilis), and small (Chrysalidocarpus madagascariensis) fruits. We integrated double-digest restriction-site-associated DNA sequencing (ddRAD) of 167 individuals from 25 populations with (past) distribution ranges for extinct and extant seed-dispersing animal species, climate and human impact data, and applied linear mixed-effects models to explore the drivers of variation in genetic diversity and genetic differentiation across Malagasy palm populations. 3. We detected higher genetic diversity in species with megafruits than in the species with small fruits, and genetic differentiation was lowest for the human-used medium-sized megafruit species. Furthermore, we found that a higher number of shared extinct megafrugivore species between palm population pairs was associated with less genetic differentiation, indicating higher gene flow, whereas no relationship with extant frugivores (that are not able to swallow and disperse the seeds) was found. Finally, genetic diversity decreased with road density, whereas genetic differentiation decreased with increasing human population density, but only for populations with megafruits. 4. Our results suggest that the legacy of megafrugivores regularly achieving long dispersal distances is still reflected in the genetic diversity and genetic differentiation of palms that were formerly dispersed by such large animals. Furthermore, high genetic diversity and low genetic differentiation were possibly maintained after the megafauna extinctions through human-mediated dispersal, long generation times, and long lifespans of these palms. Our study illustrates how integrating genetics with ecological data on species interactions, climate, and human impact, provides novel insights into the consequences of megafauna extinctions for plants with megafruits.

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How ancient forest fragmentation and riparian connectivity generate high levels of genetic diversity in a microendemic Malagasy tree

Cited by 7 publications

References 133 publications

The antique genetic plight of the Mediterranean monk seal ( Monachus monachus )

The antique genetic plight of the Mediterranean monk seal ( Monachus monachus )

The grassy ecosystems of Madagascar in context: Ecology, evolution, and conservation

Genomic signatures of past megafrugivore-mediated dispersal in Malagasy palms

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