#biogeography

An Ornithology and Biogeography question I’ve been thinking about, I wondered if you had any ideas 

Why aren’t there any native crows (genus Corvus strictly, I know there are jays) in South America? 

An explanation I read was that they would be outcompeted by toucans.

This sounds implausible, for several reasons, but especially because crows and toucans actually do overlap in range across Mexico and Central America .

Crows live in every corner of every other continent (besides obviously Antarctica), in every climate from the arctic to the Sahara to rainforests, including in various isolated islands such as Hawaii and New Caledonia.

monoliths • major earth biomes

Spectacled Bear Effigy Jar Chimu, Peru, Late Intermediate Period, c.1300-1470 Blackware, 8 x 3.75 x 4.75 in (20.3 x 9.5 x 12.1 cm) Johnson Museum of Art 56.160

treat the earth like you want her to treat you.

Behold, floof!

This wonderful little creature is the Monito del Monte, also known as the Colo Colo Opossum. They live in bamboo thickets in the tiny patch of Chile indicated below.

Now, what's so interesting about them, you might ask? (Other than the fact that they look like a pointy arboreal Autism Creature).

Despite having a range map that looks like this, ^^^ the Monito del Monte is more closely related to *every single Australian marsupial* than it is to *literally anything* else.

You see, despite their association with Australia today, marsupials actually originated in South America. Then, one lineage ended up migrating to Australia via Antarctica, which was connected to both continents for most of the Eocene.

At the time, the climate was also much warmer than it is now, with no permanent polar icecaps. Based on the (fairly limited, for obvious reasons) fossil record of Antarctica, much of it would have been a temperate forest environment, most closely resembling the sorts of biomes seen in Patagonia, Aotearoa, and Tasmania today.

In fact, many of the plants and animals living in Patagonia, Aotearoa, and Tasmania today, including the Monito del Monte, are essentially the last remnants of the ancient Antarctic ecosystems, with Eucalyptus and Southern Beech trees, as well as numerous closely related fish lineages, frogs, snails, and loads of other plant lineages. (Arguably, penguins also fit into this category, though, since they're still found in Antarctica, their distribution seems a lot less weird without context).

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They may all look the same at first glance, but today we know that there are more giraffe species than previously thought. A recent review by the International Union for Conservation of Nature (IUCN), based on original and updated data as well as expert opinions, has recognised the existence of four distinct species and several subspecies. The definition of the number of giraffe species that exist has always been a matter of debate among scientists worldwide. In fact, in 2016, it was believed that there was only one species with as many as nine subspecies. So, what led to this update? Genetic and genomic analyses carried out on existing giraffe populations have been made possible by recent scientific advances.

The assessment was conducted using the so-called “traffic light system,” already applied to other animal groups such as canids and felids. This method combines multiple converging lines of evidence: morphological/phenotypic characteristics (physical traits distinguishing one population from another), genetic data (to reconstruct close and distant relationships), and biogeographical information (showing how populations have been distributed and separated in the past and present).

The traffic light categories are:

Distinct (green): three or more independent lines of evidence indicate clear differences.

Probably distinct (yellow): multiple lines of evidence suggest differences, but further research is needed.

Unknown/Invalid (grey): little or no available evidence.

Not distinct (red): no evidence of separation, or published studies confirm conspecificity or subspecificity.

A key contribution to this review came from 3D morphometric analysis of 515 giraffe skulls from across Africa. By contrast, the coat pattern — although distinctive — is not considered a reliable criterion, as its shape and colour vary with age and population.

The combined data clearly distinguished (green light) the following species, with their respective subspecies:

Giraffa camelopardalis (G. c. antiquorum, G. c. peralta, G. c. camelopardalis)

Giraffa reticulata

Giraffa tippelskirchi (G. t. tippelskirchi, G. t. thornicrofti)

Giraffa giraffa ()

These taxonomic updates are crucial for conservation, as they provide a clearer picture of giraffe diversity and offer a solid foundation for targeted management of their populations.

See You Soon and Good Science!