|
|
Predictors of global threat in bird sister species
Štěpánková, Klára ; Reif, Jiří (advisor) ; Storchová, Lenka (referee)
Despite the threat of extinction in many bird species, it still not sufficiently known what are the biological characteristics related to this threat. This thesis tries to answer this question by analyzing the database of sister species, when we compare the traits of the threatened and unthreatened species within each species pair. This pairwise comparison should benefit from factoring, out the effects of traits shared within a given pair of species. In my thesis I use a global threat level from the IUCN classification and I relate it to latitudinal position of species geographic ranges, migration strategy, body size, habitat type and diet. I always take into account the effect of geographic range size. The range size is, often considered during the classification of threat and can also influence and the effects of other traits. Results show, besides the trivial effect of range size, when species with smaller ranges have a higher degree of threat, that the migration strategy is the only trait significantly related to the degree of threat at the global scale. Species, migrating for longer distances were more threatened than species migrating for shorter distances, probably because the former face more frequently the risks encountering many different environments and regions.
|
guest ::
RSS feed.