Person: Mairal Pisa, Mario José
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First Name
Mario José
Last Name
Mairal Pisa
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Biológicas
Department
Biodiversidad, Ecología y Evolución
Area
Botánica
Identifiers
6 results
Search Results
Now showing 1 - 6 of 6
Item A tale of two forests: ongoing aridification drives population decline and genetic diversity loss at continental scale in Afro-Macaronesian evergreen-forest archipelago endemics(Annals of Botany, 2018) Mairal Pisa, Mario José; Caujapé-Castells, Juli; Pellissier, Loïc; Jaén-Molina, Ruth; Álvarez, Nadir; Heuertz, Miriam; Sanmartín, IsabelBackground and Aims Various studies and conservationist reports have warned about the contraction of the last subtropical Afro-Macaronesian forests. These relict vegetation zones have been restricted to a few oceanic and continental islands around the edges of Africa, due to aridification. Previous studies on relict species have generally focused on glacial effects on narrow endemics; however, little is known about the effects of aridification on the fates of previously widespread subtropical lineages. • Methods Nuclear microsatellites and ecological niche modelling were used to understand observed patterns of genetic diversity in two emblematic species, widely distributed in these ecosystems: Canarina eminii (a palaeoendemic of the eastern Afromontane forests) and Canarina canariensis (a palaeoendemic of the Canarian laurel forests). The software DIYABC was used to test alternative demographic scenarios and an ensemble method was employed to model potential distributions of the selected plants from the end of the deglaciation to the present. • Key Results All the populations assessed experienced a strong and recent population decline, revealing that locally widespread endemisms may also be alarmingly threatened. • Conclusions The detected extinction debt, as well as the extinction spiral to which these populations are subjected, demands urgent conservation measures for the unique, biodiversity-rich ecosystems that they inhabit.Item Ancient vicariance and climate‐driven extinction explain continental‐wide disjunctions in Africa: the case of the Rand Flora genus Canarina (Campanulaceae)(Molecular Ecology, 2015) Mairal Pisa, Mario José; Pokorny, Lisa; Aldasoro, Juan José; Alarcón, Marisa; Sanmartín, IsabelAbstract Transoceanic distributions have attracted the interest of scientists for centuries. Less attention has been paid to the evolutionary origins of ‘continent‐wide’ disjunctions, in which related taxa are distributed across isolated regions within the same continent. A prime example is the ‘Rand Flora’ pattern, which shows sister taxa disjunctly distributed in the continental margins of Africa. Here, we explore the evolutionary origins of this pattern using the genus Canarina, with three species: C. canariensis, associated with the Canarian laurisilva, and C. eminii and C. abyssinica, endemic to the Afromontane region in East Africa, as case study. We infer phylogenetic relationships, divergence times and the history of migration events within Canarina using Bayesian inference on a large sample of chloroplast and nuclear sequences. Ecological niche modelling was employed to infer the climatic niche of Canarina through time. Dating was performed with a novel nested approach to solve the problem of using deep time calibration points within a molecular dataset comprising both above‐species and population‐level sampling. Results show C. abyssinica as sister to a clade formed by disjunct C. eminii> and C. canariensis. Miocene divergences were inferred among species, whereas infraspecific divergences fell within the Pleistocene–Holocene periods. Although C. eminii and C. canariensis showed a strong genetic geographic structure, among‐population divergences were older in the former than in the latter. Our results suggest that Canarina originated in East Africa and later migrated across North Africa, with vicariance and aridification‐driven extinction explaining the 7000 km/7 million year divergence between the Canarian and East African endemics.Item Palaeo‐islands as refugia and sources of genetic diversity within volcanic archipelagos: the case of the widespread endemic canarina canariensis (ampanulaceae)(Molecular Ecology, 2015) Mairal Pisa, Mario José; Sanmartín, Isabel; Aldasoro, Juan José; Culshaw, Victoria; Manolopoulou, Ioanna; Alarcón, MarisaGeographical isolation by oceanic barriers and climatic stability has been postulated as some of the main factors driving diversification within volcanic archipelagos. However, few studies have focused on the effect that catastrophic volcanic events have had on patterns of within‐island differentiation in geological time. This study employed data from the chloroplast (cpDNA haplotypes) and the nuclear (AFLP) genomes to examine the patterns of genetic variation in Canarina canariensis, an iconic plant species associated with the endemic laurel forest of the Canary islands. We found a strong geographical population structure, with a first divergence around 0.8 Ma that has Tenerife as its central axis and divides Canarian populations into eastern and western clades. Genetic diversity was greatest in the geologically stable ‘palaeo‐islands’ of Anaga, Teno and Roque del Conde; these areas were also inferred as the ancestral location of migrant alleles towards other disturbed areas within Tenerife or the nearby islands using a Bayesian approach to phylogeographical clustering. Oceanic barriers, in contrast, appear to have played a lesser role in structuring genetic variation, with intra‐island levels of genetic diversity larger than those between‐islands. We argue that volcanic eruptions and landslides after the merging of the palaeo‐islands 3.5 Ma played key roles in generating genetic boundaries withinTenerife, with the palaeo‐islands acting as refugia against extinction, and as cradles and sources of genetic diversity to other areas within the archipelago.Item Geographic barriers and Pleistocene climate change shaped patterns of genetic variation in the Eastern Afromontane biodiversity hotspot(Scientific Report, 2017) Mairal Pisa, Mario José; Sanmartín, Isabel; Herrero, Alberto; Pokorny, Lisa; Pablo Vargas, Pablo; Aldasoro, Juan J.; Alarcón, MarisaThe Eastern African Afromontane forest is getting increased attention in conservation studies because of its high endemicity levels and shrinking geographic distribution. Phylogeographic studies have found evidence of high levels of genetic variation structured across the Great Rift System. Here, we use the epiphytic plant species Canarina eminii to explore causal explanations for this pattern. Phylogeographic analyses were undertaken using plastid regions and AFLP fragments. Population genetic analyses, Statistical Parsimony, and Bayesian methods were used to infer genetic diversity, genealogical relationships, structure, gene flow barriers, and the spatiotemporal evolution of populations. A strong phylogeographic structure was found, with two reciprocally monophyletic lineages on each side of the Great Rift System, high genetic exclusivity, and restricted gene flow among mountain ranges. We explain this pattern by topographic and ecological changes driven by geological rifting in Eastern Africa. Subsequent genetic structure is attributed to Pleistocene climatic changes, in which sky-islands acted as long-term refuges and cradles of genetic diversity. Our study highlights the importance of climate change and geographic barriers associated with the African Rift System in shaping population genetic patterns, as well as the need to preserve the high levels of exclusive and critically endangered biodiversity harboured by current patches of the Afromontane forest.Item Living on the edge: timing of Rand Flora disjunctions congruent with ongoing aridification in Africa(Frontiers in genetics, 2015) Pokorny, Lisa; Riina, Ricarda; Mairal Pisa, Mario José; Meseguer, Andrea S.; Culshaw, Victoria; Cendoya, Jon; Serrano, Miguel; Carbajal, Rodrigo; Ortiz, Santiago; Heuertz, Myriam; Sanmartín, IsabelThe Rand Flora is a well-known floristic pattern in which unrelated plant lineages show similar disjunct distributions in the continental margins of Africa and adjacent islands—Macaronesia-northwest Africa, Horn of Africa-Southern Arabia, Eastern Africa, and Southern Africa. These lineages are now separated by environmental barriers such as the arid regions of the Sahara and Kalahari Deserts or the tropical lowlands of Central Africa. Alternative explanations for the Rand Flora pattern range from vicariance and climate-driven extinction of a widespread pan-African flora to independent dispersal events and speciation in situ. To provide a temporal framework for this pattern, we used published data from nuclear and chloroplast DNA to estimate the age of disjunction of 17 lineages that span 12 families and nine orders of angiosperms. We further used these estimates to infer diversification rates for Rand Flora disjunct clades in relation to their higher-level encompassing lineages. Our results indicate that most disjunctions fall within the Miocene and Pliocene periods, coinciding with the onset of a major aridification trend, still ongoing, in Africa. Age of disjunctions seemed to be related to the climatic affinities of each Rand Flora lineage, with sub-humid taxa dated earlier (e.g., Sideroxylon) and those with more xeric affinities (e.g., Campylanthus) diverging later. We did not find support for significant decreases in diversification rates in most groups, with the exception of older subtropical lineages (e.g., Sideroxylon, Hypericum, or Canarina), but some lineages (e.g., Cicer, Campylanthus) showed a long temporal gap between stem and crown ages, suggestive of extinction. In all, the Rand Flora pattern seems to fit the definition of biogeographic pseudocongruence, with the pattern arising at different times in response to the increasing aridity of the African continent, with interspersed periods of humidity allowing range expansions.Item Lineage‐specific climatic niche drives the tempo of vicariance in the Rand Flora(Journal of Biogeography, 2017) Mairal Pisa, Mario José; Sanmartín, Isabel; Pellissier, LoïcAbstractAimThe disjunct distribution patterns of sister taxa can arise when previously continuous distribution ranges are fragmented by environmental changes such as major climatic events. Populations become isolated on either side of the newly established environmental barrier, and absence of gene flow promotes allopatric speciation, in a process that is known as ecological vicariance. If climate change altered the ancestral range gradually, such as along temporal temperature or moisture gradients, the age of divergence of disjunct species should be related to the lineage tolerance to climatic conditions. Here, we investigate this hypothesis using as a study model the African Rand Flora, a continental‐scale floristic pattern that relates sister taxa distributed on either side of the Saharan Desert.LocationAfrica, Macaronesia, Mediterranean Basin and the Middle East.MethodsWe estimated the extant climatic tolerances of 14 Rand Flora lineages based on present occurrence data, and correlated the phylogenetic age of divergence between vicariant clades. We tested whether the tempo of the vicariance in the Rand Flora lineages was associated with the average values of their climatic niches in agreement with niche‐driven divergence. We hindcasted species ranges using species distribution models combined with palaeoclimate simulations to infer the potential distribution of each lineage's ancestors.ResultsWe found a positive relationship between the lineage temperature niche and the age of the Rand Flora disjunction: lineages with subtropical affinities diverged first, whereas those with a higher tolerance to drier conditions (temperate or sub‐xeric adaptations) exhibited younger disjunctions. The range reconstructions showed the existence of climatic corridors south of the Sahara in the wetter Late Miocene, which became interrupted during the mid‐Pliocene warming event.Main conclusionsOur results suggest that climate change leading to the formation of the Sahara Desert drove Rand Flora lineages divergences along a temporal sequence that matched the climatic niche of species.