1st example : the apple maggot fly

200 years ago, the ancestors of apple maggot flies laid their eggs only on hawthorns — but today, these flies lay eggs on hawthorns (which are native to America) and domestic apples (which were introduced to America by immigrants and bred). Females generally choose to lay their eggs on the type of fruit they grew up in, and males tend to look for mates on the type of fruit they grew up in. So hawthorn flies generally end up mating with other hawthorn flies and apple flies generally end up mating with other apple flies. This means that gene flow between parts of the population that mate on different types of fruit is reduced. This host shift from hawthorns to apples may be the first step toward speciation — in fewer than 200 years, some genetic differences between these two groups of flies have evolved. NB : the Apple Maggot (Rhagoletis pomonella), also known as a "railroad worm" is a pest of several fruits, mainly apples.

So which type of speciation ? Allopatric

Peripatric

Parapatric

Sympatric

Why ? → find arguments in the text to explain your choice (at oral) and give below a definition to this type of speciation Speciation which does not require large-scale geographic distance to reduce gene flow between parts of a population. It may happen when a group within the population exploits a new niche reducing gene flow with individuals exploiting the other niche. Other exemple : Cychlid fish in the lake Tanganyika (Tanzania)

2nd example : the californian salamander

So which type of speciation ? Allopatric

Peripatric

Parapatric

Sympatric

Why ? → find arguments in the text to explain your choice (at oral) and give below a definition to this type of speciation In parapatric speciation, two subpopulations of a species evolve reproductive isolation from one another while continuing to exchange genes. This mode of speciation has three distinguishing characteristics: 1) mating occurs non-randomly, 2) gene flow occurs unequally, and 3) populations exist in either continuous or discontinuous geographic ranges. This distribution pattern may be the result of unequal dispersal, incomplete geographical barriers, or divergent expressions of behavior, among other things. Parapatric speciation predicts that hybrid zones will often exist at the junction between the two populations. Other example : seagulls

3rd example : the Azores bullfinch

Pyrrhula murina (endemic from São Miguel)

Pyrrhula pyrrhula (from continent, Eurasia)

Azorean native passeriformes can act as a model species for evolutionary studies beacause, from the majority of the that are known to have colonized islands, they show smaller dispersal rates and reduced gene flow between islands and continents due to a great geographical isolation, hence increasing the probability of population differentiation. Recent decades have seen several studies focusing the phylogeography and the genetic diversity of the Azores passerines, raising new theories about the colonization of the Azores and the natural evolution of species on isolated archipelagos. Based on the genetic studies of the genus Pyrrhula from Eurasia (Töpfer et al, 2010) that revealed the genetic distance of the Azores bullfinch to other bullfinches' populations, it was possible to assign a species status to Pyrrhula murina from São Miguel island. (Source : Pedro Rodrigues). Did you know? This bird is the most endangered one in Europe! Thanks to the Priolo association for protecting the bullfinch habitat in Nordeste where it lives in São Miguel island, Azores. So which type of speciation ? Allopatric

Peripatric

Parapatric

Sympatric

Why ? → find arguments in the text to explain your choice (at oral) and give below a definition to this type of speciation Regarded as the most common type of speciation, allopatric speciation involves the physical separation of a species into two groups. This may occur due to climatic changes, movement of tectonic plates leading to the fragmentation of a mass of land, or eruption of a land mass, formation of waterways, or due to the presence of an impassable mountain range. Other example : the endemic bat Nyctalus azoreum

4th example : the polar bear

Left : the brown bear ; Right : the polar bear

The red shading indicates the range of the brown bear. The blue shading indicates the range of the polar bear. The purple shading indicates areas where both live. Polar bears' ancestors moved to a new ecological niche on the periphery of the brown bears' original habitat. So which type of speciation ? Allopatric

Peripatric

Parapatric

Sympatric

Why ? → find arguments in the text to explain your choice (at oral) and give below a definition to this type of speciation Peripatric speciation is a form of speciation, the formation of new species through evolution. In this form, new species are formed in isolated peripheral populations; this is similar to allopatric speciation in that populations are isolated and prevented from exchanging genes. However, peripatric speciation, unlike allopatric speciation, proposes that one of the populations is much smaller than the other. Peripatric speciation was originally proposed by Ernst Mayr, and is related to the founder effect, because small living populations may undergo selection bottlenecks. The founder-effect is based on models that suggest peripatric speciation can occur by the interaction of selection and genetic drift. Other interesting sites : https://biologywise.com/basic-modes-of-speciation https://evolution.berkeley.edu/evolibrary/news/100201_speciation A video worth to be watched : https://www.youtube.com/watch?v=qUDATsOFCZk