Gilbert K.,1101 W. 8th St. |
Long E.,26847 Johnson Creek Rd. |
Micha' B.,National University of Guinea Ecuatorial |
Quinn R.,103 Ortley Ave. |
Hausdorf B.,University of Hamburg
Journal of Molluscan Studies | Year: 2014
We investigated the land-snail fauna of rain forests on the eastern slopes of Pico Biao on Bioko Island in the Gulf of Guinea. Thirty-seven plots were studied along an altitudinal transect reaching from sea level (lowland rain forest) to an altitude of 1,830 m (mossy forest). A total of 1,755 specimens were collected and were assigned to 68 land-snail species. Eleven species were new records for Bioko. At least 15 of the recorded species are endemic to Bioko. The degree of endemism was high in mossy forest (23%) and in lowland rain forest (20%), but lower in montane forest (8%). Species richness showed a hump-shaped distribution along the altitudinal gradient with a maximum at 500 m a.s.l. Species richness peaked in forests in which there had been selective logging more than 50 years ago, indicating that some disturbance may have beneficial effects on biodiversity. Species richness was correlated with the thickness of leaf litter. The availability and quality of suitable microhabitats is more important for the occurrence of snail species than gradients of otherwise often decisive environmental parameters like temperature, which are strongly correlated with altitude. A lack of clustering of the occurrences of different snail species along the altitudinal gradient indicated a Gleasonian meta-community structure with individualistic responses of the various species to environmental parameters. No negative co-occurrence patterns that might provide evidence for interspecific competition could be detected. The frequent coexistence of morphologically similar, and presumably ecologically equivalent, congeneric species may indicate that such equivalents do not exclude each other as predicted by the neutral theory of biodiversity. However, current knowledge about individual snail species is too scanty to exclude the possibility that niches of congeneric species differ in some details. © The Author 2014.
Tene Fossog B.,IRD Montpellier |
Tene Fossog B.,Laboratoire Of Recherche Sur Le Paludisme |
Tene Fossog B.,University of Yaounde I |
Ayala D.,IRD Montpellier |
And 19 more authors.
Evolutionary Applications | Year: 2015
Understanding how divergent selection generates adaptive phenotypic and population diversification provides a mechanistic explanation of speciation in recently separated species pairs. Towards this goal, we sought ecological gradients of divergence between the cryptic malaria vectors Anopheles coluzzii and An. gambiae and then looked for a physiological trait that may underlie such divergence. Using a large set of occurrence records and eco-geographic information, we built a distribution model to predict the predominance of the two species across their range of sympatry. Our model predicts two novel gradients along which the species segregate: distance from the coastline and altitude. Anopheles coluzzii showed a 'bimodal' distribution, predominating in xeric West African savannas and along the western coastal fringe of Africa. To test whether differences in salinity tolerance underlie this habitat segregation, we assessed the acute dose-mortality response to salinity of thirty-two larval populations from Central Africa. In agreement with its coastal predominance, Anopheles coluzzii was overall more tolerant than An. gambiae. Salinity tolerance of both species, however, converged in urban localities, presumably reflecting an adaptive response to osmotic stress from anthropogenic pollutants. When comparing degree of tolerance in conjunction with levels of syntopy, we found evidence of character displacement in this trait. © 2015 John Wiley & Sons Ltd84 April 2015 10.1111/eva.12242 Original Article Original Articles © 2014 The Authors. Evolutionary Applications published by John Wiley & Sons Ltd.
Honarvar S.,Indiana University - Purdue University Fort Wayne |
Fitzgerald D.B.,Texas A&M University |
Weitzman C.L.,University of Nevada, Reno |
Sinclair E.M.,Indiana University - Purdue University Fort Wayne |
And 3 more authors.
Chelonian Conservation and Biology | Year: 2016
Bioko Island's southern beaches are important nesting sites for marine turtles in the Gulf of Guinea region. In this study, we present data on the 4 species of sea turtles nesting on 5 nesting beaches (19 km) of Bioko Island, from 2000 to 2014. A total of 43,860 leatherback (Dermochelys coriacea), 16,778 green (Chelonia mydas), 1731 olive ridley (Lepidochelys olivacea), and 85 hawksbill turtle (Eretmochelys imbricata) encounters, defined as the number of tracks, were recorded on Bioko's southern beaches. Since 2008, the estimated number of leatherback females ranged from 42 to 444, green turtles from 63 to 649, and olive ridley turtles from 22 to 53 annually. This study presents the first extensive tagging program on Bioko Island, where 790 leatherback turtles were tagged with Passive Integrated Transponder tags from 2008 to 2014. Only 6.1% of the tagged turtles returned to nest again with a remigration interval of 3-4 yrs. In addition, 279 green turtles were flipper-tagged in the 2013-2014 nesting season. Overall, the total number of leatherback turtle encounters decreased annually from 2000 to 2014. These declines may be attributed to adult turtle captures in commercial fisheries operating in the Gulf of Guinea and turtle take in local artisanal fisheries. On the other hand, olive ridley encounters increased from 2000 to 2014. The construction of a paved road from Luba, the second largest city on Bioko Island, directly to the nesting beaches is now set to dramatically alter human interaction with nesting turtles. These long-term data confirm the importance of Bioko Island's nesting beaches for the Southeast Atlantic and fill a critical need for sea turtle conservation in a data-deficient, yet globally significant, area. © 2016 Chelonian Research Foundation.
Rodriguez-Prieto I.,CSIC - National Museum of Natural Sciences |
Ondo-Nguema E.,National University of Guinea Ecuatorial |
Sima T.,National University of Guinea Ecuatorial |
Osa-Akara L.B.,National University of Guinea Ecuatorial |
Abeso E.,National University of Guinea Ecuatorial
North-Western Journal of Zoology | Year: 2010
In this work we describe and discuss the first record of a reptile species using the constructions of solitary insects as egg-laying substrata. Annobon dwarf geckoes (Lygodactylus thomensis wermuthi) were found to lay eggs in mud-nests of solitary wasps in Annobon Island, Equatorial Guinea. This unusual nesting association may be common in the studied gecko, since we found seven gecko clutches in wasp nests situated at different locations, while no other nesting substrata were found for this taxon. © NwjZ, Oradea, Romania, 2010.