Phylogeography and genetic diversity ofOphidiaster ophidianus(Echinodermata: Asteroidea)—evidence for a recent range expansion in the Azores

2014 ◽  
Vol 94 (7) ◽  
pp. 1475-1484 ◽  
Author(s):  
J. Micael ◽  
P. Rodrigues ◽  
A.C. Costa ◽  
M.J. Alves
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Genetic Differentiation ◽  
Mediterranean Sea ◽  
North Atlantic ◽  
Range Expansion ◽  
Mitochondrial Gene ◽  
Protected Species ◽  
The Mediterranean

The seastarOphidiaster ophidianusis a vulnerable and protected species in the Mediterranean Sea but is common on North Atlantic islands such as the Azores and Madeira archipelagos. This work presents new insights into the phylogeography and genetic diversity ofO. ophidianusfrom the Azores, based on 67 sequences of the 16S mitochondrial gene and 46 sequences of the nuclear ATP intron 5 gene. Twenty-six samples from the Mediterranean and seven samples from Madeira were used as out-groups. The results revealed that there is a lack of genetic differentiation betweenO. ophidianusfrom the Azores and the out-groups. All, therefore, belong to the same lineage and argue for a fast and recent range expansion of this species into the Azores. Our results also suggest the existence of distinctive periods of strong gene flow followed by periods of either low or non-existent gene flow between the Mediterranean Sea and this archipelago, which could explain the presence of private haplotypes in all studied areas.

scholarly journals Mitogenomics of the endangered Mediterranean monk seal (Monachus monachus) reveals dramatic loss of diversity and supports historical gene-flow between Atlantic and eastern Mediterranean populations

2020 ◽  
Author(s):  
Alba Rey-Iglesia ◽  
Philippe Gaubert ◽  
Gonçalo Espregueira Themudo ◽  
Rosa Pires ◽  
Constanza De La Fuente ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
North Atlantic ◽  
Marine Mammals ◽  
Eastern Mediterranean ◽  
The Black Sea ◽  
Mediterranean Populations ◽  
Geographic Ranges ◽  
Western Sahara ◽  
The Mediterranean

Abstract The Mediterranean monk seal Monachus monachus is one of the most threatened marine mammals, with only 600–700 individuals restricted to three populations off the coast of Western Sahara and Madeira (North Atlantic) and between Greece and Turkey (eastern Mediterranean). Its original range was from the Black Sea (eastern Mediterranean) to Gambia (western African coast), but was drastically reduced by commercial hunting and human persecution since the early stages of marine exploitation. We here analyse 42 mitogenomes of Mediterranean monk seals, from across their present and historical geographic ranges to assess the species population dynamics over time. Our data show a decrease in genetic diversity in the last 200 years. Extant individuals presented an almost four-fold reduction in genetic diversity when compared to historical specimens. We also detect, for the first time, a clear segregation between the two North Atlantic populations, Madeira and Cabo Blanco, regardless of their geographical proximity. Moreover, we show the presence of historical gene-flow between the two water basins, the Atlantic Ocean and the Mediterranean Sea, and the presence of at least one extinct maternal lineage in the Mediterranean. Our work demonstrates the advantages of using full mitogenomes in phylogeographic and conservation genomic studies of threatened species.

scholarly journals Genetic diversity increases with depth in red gorgonian populations of the Mediterranean Sea and the Atlantic Ocean

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6794 ◽  
Author(s):  
Joanna Pilczynska ◽  
Silvia Cocito ◽  
Joana Boavida ◽  
Ester A. Serrão ◽  
Jorge Assis ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Thermal Stress ◽  
Gene Flow ◽  
Atlantic Ocean ◽  
Mediterranean Sea ◽  
Environmental Conditions ◽  
Heat Waves ◽  
Genetic Erosion ◽  
Linear Pattern ◽  
The Mediterranean

Background In the ocean, the variability of environmental conditions found along depth gradients exposes populations to contrasting levels of perturbation, which can be reflected in the overall patterns of species genetic diversity. At shallow sites, resource availability may structure large, persistent and well-connected populations with higher levels of diversity. In contrast, the more extreme conditions, such as thermal stress during heat waves, can lead to population bottlenecks and genetic erosion, inverting the natural expectation. Here we examine how genetic diversity varies along depth for a long-lived, important ecosystem-structuring species, the red gorgonian, Paramuricea clavata. Methods We used five polymorphic microsatellite markers to infer differences in genetic diversity and differentiation, and to detect bottleneck signs between shallow and deeper populations across the Atlantic Ocean and the Mediterranean Sea. We further explored the potential relationship between depth and environmental gradients (temperature, ocean currents, productivity and slope) on the observed patterns of diversity by means of generalized linear mixed models. Results An overall pattern of higher genetic diversity was found in the deeper sites of the Atlantic Ocean and the Mediterranean Sea. This pattern was largely explained by bottom temperatures, with a linear pattern of decreasing genetic diversity with increasing thermal stress. Genetic differentiation patterns showed higher gene flow within sites (i.e., shallow vs. deeper populations) than between sites. Recent genetic bottlenecks were found in two populations of shallow depths. Discussion Our results highlight the role of deep refugial populations safeguarding higher and unique genetic diversity for marine structuring species. Theoretical regression modelling demonstrated how thermal stress alone may reduce population sizes and diversity levels of shallow water populations. In fact, the examination of time series on a daily basis showed the upper water masses repeatedly reaching lethal temperatures for P. clavata. Differentiation patterns showed that the deep richer populations are isolated. Gene flow was also inferred across different depths; however, not in sufficient levels to offset the detrimental effects of surface environmental conditions on genetic diversity. The identification of deep isolated areas with high conservation value for the red gorgonian represents an important step in the face of ongoing and future climate changes.

scholarly journals Evolutionary history and genetic connectivity across highly fragmented populations of an endangered daisy

Heredity ◽  
2021 ◽  
Author(s):  
Yael S. Rodger ◽  
Alexandra Pavlova ◽  
Steve Sinclair ◽  
Melinda Pickup ◽  
Paul Sunnucks
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Genetic Differentiation ◽  
Evolutionary History ◽  
Livestock Grazing ◽  
Genetic Connectivity ◽  
Evolutionary Divergence ◽  
Common Component ◽  
A Genome ◽  
Eastern Australia

AbstractConservation management can be aided by knowledge of genetic diversity and evolutionary history, so that ecological and evolutionary processes can be preserved. The Button Wrinklewort daisy (Rutidosis leptorrhynchoides) was a common component of grassy ecosystems in south-eastern Australia. It is now endangered due to extensive habitat loss and the impacts of livestock grazing, and is currently restricted to a few small populations in two regions >500 km apart, one in Victoria, the other in the Australian Capital Territory and nearby New South Wales (ACT/NSW). Using a genome-wide SNP dataset, we assessed patterns of genetic structure and genetic differentiation of 12 natural diploid populations. We estimated intrapopulation genetic diversity to scope sources for genetic management. Bayesian clustering and principal coordinate analyses showed strong population genetic differentiation between the two regions, and substantial substructure within ACT/NSW. A coalescent tree-building approach implemented in SNAPP indicated evolutionary divergence between the two distant regions. Among the populations screened, the last two known remaining Victorian populations had the highest genetic diversity, despite having among the lowest recent census sizes. A maximum likelihood population tree method implemented in TreeMix suggested little or no recent gene flow except potentially between very close neighbours. Populations that were more genetically distinctive had lower genetic diversity, suggesting that drift in isolation is likely driving population differentiation though loss of diversity, hence re-establishing gene flow among them is desirable. These results provide background knowledge for evidence-based conservation and support genetic rescue within and between regions to elevate genetic diversity and alleviate inbreeding.

High genetic differentiation of red gorgonian populations from the Atlantic Ocean and the Mediterranean Sea

2017 ◽  
Vol 13 (8) ◽  
pp. 854-861 ◽  
Author(s):  
Joanna Pilczynska ◽  
Silvia Cocito ◽  
Joana Boavida ◽  
Ester A. Serrão ◽  
Henrique Queiroga
Keyword(s):  
Genetic Differentiation ◽  
Atlantic Ocean ◽  
Mediterranean Sea ◽  
The Mediterranean

scholarly journals Serial founder effects and genetic differentiation during worldwide range expansion of monarch butterflies

2014 ◽  
Vol 281 (1797) ◽  
pp. 20142230 ◽  
Author(s):  
Amanda A. Pierce ◽  
Myron P. Zalucki ◽  
Marie Bangura ◽  
Milan Udawatta ◽  
Marcus R. Kronforst ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Genetic Differentiation ◽  
Genetic Drift ◽  
North American ◽  
Range Expansion ◽  
Dispersal Ability ◽  
Founder Effects ◽  
Long Distance ◽  
Mobile Species ◽  
High Dispersal

Range expansions can result in founder effects, increasing genetic differentiation between expanding populations and reducing genetic diversity along the expansion front. However, few studies have addressed these effects in long-distance migratory species, for which high dispersal ability might counter the effects of genetic drift. Monarchs ( Danaus plexippus ) are best known for undertaking a long-distance annual migration in North America, but have also dispersed around the world to form populations that do not migrate or travel only short distances. Here, we used microsatellite markers to assess genetic differentiation among 18 monarch populations and to determine worldwide colonization routes. Our results indicate that North American monarch populations connected by land show limited differentiation, probably because of the monarch's ability to migrate long distances. Conversely, we found high genetic differentiation between populations separated by large bodies of water. Moreover, we show evidence for serial founder effects across the Pacific, suggesting stepwise dispersal from a North American origin. These findings demonstrate that genetic drift played a major role in shaping allele frequencies and created genetic differentiation among newly formed populations. Thus, range expansion can give rise to genetic differentiation and declines in genetic diversity, even in highly mobile species.

The reproductive biology of swordfish (Xiphias gladius) in the Strait of Gibraltar

2018 ◽  
Vol 99 (3) ◽  
pp. 649-659 ◽  
Author(s):  
Noureddine Abid ◽  
Amin Laglaoui ◽  
Abdelhay Arakrak ◽  
Mohammed Bakkali
Keyword(s):  
Mediterranean Sea ◽  
North Atlantic ◽  
Fork Length ◽  
Strait Of Gibraltar ◽  
Mixing Rate ◽  
The North ◽  
Lower Jaw ◽  
The North Atlantic ◽  
The Mediterranean ◽  
First Maturity

During the period from April to September for the years 2014–2016, 998 swordfishes caught by the Moroccan artisanal longline fishery in the Strait of Gibraltar were sampled to study the reproduction of this species in this mixing area between the Mediterranean Sea and the North Atlantic. The results showed that the sex ratio is slightly in favour of males for sizes smaller than 130 cm LJFL (Lower jaw-fork length), whereas females are more numerous in sizes larger than 140 cm LJFL. Fifty per cent of females were estimated to be mature at 170 cm LJFL, while for males, the size at first maturity was estimated to be 95 cm LJFL. The swordfish spawn from June to September, probably in the Mediterranean Sea. The findings of this study suggest that the reproductive characteristics of swordfish caught in the Strait of Gibraltar are similar to those of the Mediterranean swordfish, and a high mixing rate between the Mediterranean and the North Atlantic stocks occurs in the study area.

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