Melbourne, Jul 15 (The Conversation) The snow petrel, a remarkably white bird distinguished by its black eyes and beak, is one of only three bird species ever recorded at the South Pole. Antarctica is the solitary habitat for this species on Earth.
It shares this exclusivity with numerous other species, as both Antarctica and the sub-Antarctic regions are home to a significant number of species endemic to these areas — meaning they exist nowhere else. This high degree of "endemism" is crucial for directing species conservation efforts.
However, our latest research reveals that the extent of endemism in Antarctica, the sub-Antarctic, and the broader southern hemisphere has often been underestimated.
Understanding the true level of endemism is vital. Regions with high endemism host species that have limited ranges, unique evolutionary progressions, and distinct ecological roles, making them particularly susceptible to threats such as climate change, major habitat changes, and invasive species.
If these levels are underestimated, conservation efforts may risk neglecting areas that shelter irreplaceable bird species.
Measuring Bias in Endemism Globally, endemism patterns aren't accurately defined for two main reasons. First, the most routine method for computing endemism tends to favor regions with a higher overall number of species, known as species richness.
Second, global diversity studies often leave out regions with fewer species, primarily located in the southern hemisphere, notably Antarctica. Excluding these species-scarce sites distorts endemism estimates for other areas.
An alternative measure, focusing on "complementarity," evaluates whether species at a site exist elsewhere. This method pinpoints areas with the highest proportion of species with restricted ranges.
At such highly endemic sites, local ecosystems are heavily reliant on these range-restricted species, emphasizing their irreplaceable nature.
Global Endemism Hotspots In our new study, we've used this approach to reassess bird endemism worldwide. We also evaluated other dimensions of bird diversity, examining endemism in terms of the irreplaceable evolutionary history and ecological functions they embody at different sites.
The results indicate that southern-hemisphere bird communities exhibit higher local endemism rates compared to those in the northern hemisphere across all diversity aspects. Sub-Antarctic islands, the High Andes, as well as select regions in Australia, New Zealand (Aotearoa), and southern Africa, emerge as global endemism epicenters.
These locations are home to numerous charismatic birds with distinct evolutionary paths and ecological roles, predominantly found in the southern hemisphere. Among them are the palaeognaths, which include kiwis, emus, cassowaries, and ostriches, along with lyrebirds, New Zealand wrens, and iconic Antarctic species like penguins and albatrosses.
Limited Land, Vast Oceans The heightened endemism rates in the southern hemisphere can be attributed to the unequal global landmass distribution. Simply put, there is substantially more land in the northern hemisphere.
As you move southward, the landmasses are increasingly separated by extensive oceanic spaces. This separation leads to southern hemisphere species having smaller ranges compared to their northern counterparts, resulting in fewer shared species among local communities and higher endemism.
Increased Vulnerability Our findings suggest that birds in both hemispheres might respond differently to environmental stressors. Yet, most studies on climate change impacts have targeted the northern hemisphere.
As climates shift, species will likely seek cooler climates, meaning northern-hemisphere birds can migrate broadly across uninterrupted lands. Conversely, southern-hemisphere birds face constraints due to vast oceans separating their habitats.
For species residing in the southernmost areas of South America, Africa, or Australia, the only major landmass further south is Antarctica, which is generally inhospitable to most bird species.
The potentially heightened vulnerability of southern-hemisphere birds underlines the need for enhanced protection. Conservation strategies should focus not only on known biodiversity hotspots that feature numerous species but also on regions with limited, irreplaceable species found nowhere else. (The Conversation) GRS GRS
(Only the headline of this report may have been reworked by Editorji; the rest of the content is auto-generated from a syndicated feed.)
