The black-headed siskin (''Spinus notatus''), also known as the Jonny Bee, is a species of

finch The true finches are small to medium-sized passerine birds in the family Fringillidae. Finches have stout conical bills adapted for eating seeds and nuts and often have colourful plumage. They occupy a great range of habitats where they are usua ...

in the family

Fringillidae The true finches are small to medium-sized passerine birds in the family Fringillidae. Finches have stout conical bills adapted for eating seeds and nuts and often have colourful plumage. They occupy a great range of habitats where they are usua ...

. It is found in

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

Belize Belize (; bzj, Bileez) is a Caribbean and Central American country on the northeastern coast of Central America. It is bordered by Mexico to the north, the Caribbean Sea to the east, and Guatemala to the west and south. It also shares a wate ...

, El Salvador, Guatemala, Honduras, and

Nicaragua Nicaragua (; ), officially the Republic of Nicaragua (), is the largest country in Central America, bordered by Honduras to the north, the Caribbean to the east, Costa Rica to the south, and the Pacific Ocean to the west. Managua is the countr ...

. Its natural

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

s are subtropical or tropical moist

montane forest Montane ecosystems are found on the slopes of mountains. The alpine climate in these regions strongly affects the ecosystem because temperatures fall as elevation increases, causing the ecosystem to stratify. This stratification is a crucial ...

and heavily degraded former forest.

Evolution and systematics

This species is part of a rapid recent adaptive radiation of '' Spinus'' finches in Central and South America, which produced at least eight other recognized species: '' S. atratus'', '' S. crassirostris'', '' S. spinescens'', '' S. yarrellii'', '' S. magellanicus'', '' S. olivaceus'', '' S. xanthogastrus'', and '' S. barbatus.'' The black-headed siskin was the earliest of these species to diverge. It was originally proposed that the radiation occurred around 3.5 million years ago, when an ancestral form, perhaps similar to the modern-day black-headed siskin, was able to adaptively radiate into

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sout ...

. In this version of events, the dispersal into South America happened before the isthmus of Panama was complete (around 2.7 million years ago), but when mesothermal montane plant species were able to disperse across the narrowing strait. The novel plant communities in South America would have created many new niches into which the ancestral species adaptively radiated. More recent work suggests the species radiation happened much later, within the last 1 million years, and posits the radiation happened due to climate change in the late

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in ...

. The changing climate could have fragmented various habitats in the

Andes The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long, wide (widest between 18°S – 20°S ...

, initiating

allopatric speciation Allopatric speciation () – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model – is a mode of speciation that occurs when biological populations become geographically isolated from ...

Closing of Panama Isthmus and Spinus-Carduelis notata South American evolutive radiation

Evolution and systematics

References

Further reading