2024-03-28T12:48:25Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/284242018-07-16T10:49:37Zcom_10261_24com_10261_8col_10261_277
2010-10-14T08:42:31Z
urn:hdl:10261/28424
Biotic diversification in the Guayana Highlands: a proposal
Rull, Valentí
Biodiversity
Climate change
Diversification
Endemism
Guayana Highlands,
Neotropics
Palaeoclimatology
Palaeoecology
South America
Speciation
7 p.
[EN] Until recently, the high degree of diversity and endemism of the Guayana
Highlands was explained within the frame of the refuge theory. Although this
hypothesis is unsupported by recent palaeoecological evidence, no new diversification
model has been proposed. This paper is a proposal based on the latest
palynological findings that indicate a downward biotic migration of c. 1100 m
altitude during glacials, and the subsequent interglacial upward shift, in response
to colder and warmer climates, respectively. Therefore, during glacials, biotic
mixing is expected in the lowlands, thus promoting sympatric speciation,
hybridization and polyploidy. At the mountaintops, unknown cold-adapted taxa
and pa´ramo-like(?) communities are expected to have occurred, and vicariance
prevailed. In the interglacials, many taxa have had the opportunity for ascending
to the mountains again, allowing genetic interchange among their slopes and
summits, while others would have been adapted to lowlands. The interglacial
highland communities, where vicariance still predominated, experienced some
extinction owing to habitat loss by upland displacement. According to this model,
the successive alternation of glacials and interglacials resulted in a net increase of
diversity and endemism, favoured by the complex topography and habitat heterogeneity,
which allowed high niche diversification. This model has some
similarities with the Andean and Amazon modes of diversification, but the special
topographical characteristics of the Guayana region made it different in other
fundamental aspects. The Guayana Highlands would have acted as a ‘biodiversity
pump’ for the surrounding inner and coastal lowlands, due to the repeated
speciation and further spreading events, as a response to climate. Several working
hypotheses are suggested in relation to the proposed model. The use of coordinated
international multiproxy projects combining palaeoecology and genetic
analysis of modern taxa is strongly encouraged for exploring these ideas.
2010-10-14T08:42:31Z
2010-10-14T08:42:31Z
2005
artículo
Journal of Biogeography 32(6): 921–927 (2005)
1365-2699
http://hdl.handle.net/10261/28424
10.1111/j.1365-2699.2005.01252.x
eng
http://dx.doi.org/10.1111/j.1365-2699.2005.01252.x
closedAccess
Wiley-Blackwell