Phylogeography and species distribution modelling reveal the effects of the Pleistocene ice ages on an intertidal limpet from the south-eastern Pacific

2018 ◽  
Vol 45 (8) ◽  
pp. 1751-1767 ◽  
Author(s):  
María Cecilia Pardo-Gandarillas ◽  
Christian M. Ibáñez ◽  
Felipe I. Torres ◽  
Víctor Sanhueza ◽  
Alejandra Fabres ◽  
...  
Keyword(s):  
Species Distribution ◽  
Species Distribution Modelling ◽  
Eastern Pacific ◽  
Ice Ages ◽  
The South ◽  
Distribution Modelling ◽  
South Eastern ◽  
Intertidal Limpet

scholarly journals The influence of Pleistocene dynamics on the South African salt marsh species Sarcocornia pillansii (Moss) A. J. Scott (Amaranthaceae): Inferences from phylogeography and species distribution modelling

2018 ◽  
Author(s):  
Dimitri A Veldkornet ◽  
Anusha Rajkaran ◽  
Janine B Adams
Keyword(s):  
Salt Marsh ◽  
Continental Shelf ◽  
Sea Level ◽  
Species Distribution ◽  
River Estuary ◽  
Species Distribution Modelling ◽  
The South ◽  
The West ◽  
Distribution Modelling ◽  
Salt Marsh Species

Glacial–interglacial climate oscillations during the Pleistocene played a significant role in shifting species distributions. During this period (26 500 - 19 000 years ago) the sea level was 120 m lower than it is currently with large areas of the Southern African continental shelf being exposed. This formed a barrier to cold-water dispersal of various aquatic organisms between the west and east coast. This study explores the influence of past climatic conditions on the salt marsh species Sarcocornia pillansii (Moss) A. J. Scott using species distribution modelling and multi-locus phylogeography. The area under curve (AUC) values were considered ‘good’ (> 0.80), indicating that the models had high specificity and sensitivity. The AUC was greater for the Maxent model (AUC = 0.881) compared to the Bioclim model (AUC = 0.837) under current conditions. Climate simulation of the Last Glacial Maximum (LGM) indicated greatest habitat suitability in estuaries along the west (Orange River Estuary to Langebaan) and east (Algoa Bay to Keiskamma) coast of South Africa. This pattern is reflected in the phylogeographic analysis where a greater number of haplotypes were found in estuaries west and east of the greater continental shelf. The nuclear DNA dataset that included 97 sequences eight ribotypes whereas the chloroplast DNA for 94 sequences that were resolved into four haplotypes. The results suggest that species survived in these estuaries (as refugia) during Pleistocene climate cycles. Post-LGM increases in sea level along the south coast allowed confluence between isolated river systems, offering opportunities for dispersal among populations.

scholarly journals The influence of Pleistocene dynamics on the South African salt marsh species Sarcocornia pillansii (Moss) A. J. Scott (Amaranthaceae): Inferences from phylogeography and species distribution modelling

2018 ◽  
Author(s):  
Dimitri A Veldkornet ◽  
Anusha Rajkaran ◽  
Janine B Adams
Keyword(s):  
Salt Marsh ◽  
Continental Shelf ◽  
Sea Level ◽  
Species Distribution ◽  
River Estuary ◽  
Species Distribution Modelling ◽  
The South ◽  
The West ◽  
Distribution Modelling ◽  
Salt Marsh Species

Glacial–interglacial climate oscillations during the Pleistocene played a significant role in shifting species distributions. During this period (26 500 - 19 000 years ago) the sea level was 120 m lower than it is currently with large areas of the Southern African continental shelf being exposed. This formed a barrier to cold-water dispersal of various aquatic organisms between the west and east coast. This study explores the influence of past climatic conditions on the salt marsh species Sarcocornia pillansii (Moss) A. J. Scott using species distribution modelling and multi-locus phylogeography. The area under curve (AUC) values were considered ‘good’ (> 0.80), indicating that the models had high specificity and sensitivity. The AUC was greater for the Maxent model (AUC = 0.881) compared to the Bioclim model (AUC = 0.837) under current conditions. Climate simulation of the Last Glacial Maximum (LGM) indicated greatest habitat suitability in estuaries along the west (Orange River Estuary to Langebaan) and east (Algoa Bay to Keiskamma) coast of South Africa. This pattern is reflected in the phylogeographic analysis where a greater number of haplotypes were found in estuaries west and east of the greater continental shelf. The nuclear DNA dataset that included 97 sequences eight ribotypes whereas the chloroplast DNA for 94 sequences that were resolved into four haplotypes. The results suggest that species survived in these estuaries (as refugia) during Pleistocene climate cycles. Post-LGM increases in sea level along the south coast allowed confluence between isolated river systems, offering opportunities for dispersal among populations.

Age and growth of the shortfin mako (Isurus oxyrinchus) in the south-eastern Pacific off Chile

2009 ◽  
Vol 60 (5) ◽  
pp. 394 ◽  
Author(s):  
Francisco Cerna ◽  
Roberto Licandeo
Keyword(s):  
Growth Parameters ◽  
Eastern Pacific ◽  
Age And Growth ◽  
The South ◽  
Age Classes ◽  
Vertebral Centra ◽  
South Eastern ◽  
Isurus Oxyrinchus ◽  
Shortfin Mako ◽  
Longline Fisheries

The shortfin mako, Isurus oxyrinchus, is a large pelagic shark with a widespread global distribution. However, very little is known about most aspects of this species for the south-eastern Pacific. In the present paper, the age and growth parameters of the shortfin mako, caught by Chilean swordfish longline fisheries from 2004 to 2005, are reported. Ages were estimated by counting band-pairs from sections of vertebral centra from 547 individuals, ranging from 76 to 330 cm in total length (TL). Trends in the proportion of opaque edges for all ages combined and grouped into ages 0–6 and 7–26 years indicated that they are formed during summer and showed that annually, one band-pair is formed in the vertebrae of shortfin makos. Modal-progression analysis was used to verify the first three age classes (ages 0–2 years). For both sexes, the oldest estimated age was 25+ years. Von Bertalanffy growth parameters were estimated at L∞ = 325.29 cm TL, K = 0.076 year–1 and t0 = –3.18 years for females and L∞ = 296.60 cm TL, K = 0.087 year–1 and t0 = –3.58 years for males. The results indicated that this species is highly vulnerable to exploitation and, thus, urgent conservation measures are required.

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