A Case Study in Speciation Hawthorn trees are native to North America Hawthorn fruits range between 5 mm and 20 mm in diameter with an average of 12 6 mm The hawthorn fruit is eaten by the larvae of the hawthorn maggot fly Rhagoletis pomonella The female lays fertilized eggs in the fruit Maggots larvae emerge from the egg feed on the fruit and grow through several molts To stay safe these maggots burrow into the fruit as they grow Healthy maggots drop from the tree with the fruit and burrow in the soil Pupation takes place in the soil Adult maggot flies emerge from the soil and fly to fruit trees where they mate on the surface of the fruit Hawthorn maggot flies are parasitized by parasitoid wasps that lay eggs in the maggot s body paralyzing and ultimately killing the maggot One way the flies avoid these parasitoid wasps is by burrowing into the fruit Domesticated apples Malus domesticus were introduced to North American in the 1600s They are the most widely grown frui t in North America A typical commercial apple has a diameter of 70 mm When apples were introduced to North America the larva of Rhagoletis pomonella started feeding on them The large apple fruit provides 220 times more food than hawthorn fruit but nutritionally the quality of hawthorn fruit is superior However the apples are larger so the flies can make deeper burrows to avoid parasitoid wasps It has been observed that apple maggots carry fewer parasitoid wasp eggs than hawthorn maggots do One study shows that 52 of hawthorn maggots those that live on the hawthorn fruits survive while only 27 of maggots raised on apples survive Scientists studying the hawthorn maggot flies have found that Hawthorn and apple maggot flies are physically indistinguishable However they are genetically distinct with different genetic profiles While there is no geographic isolation or physical separation between hawthorn and apple maggot flies they do prefer to mate with other flies from the same type of fruit For example flies born on apple trees will usually mate with other flies born on apple trees There is only a 4 6 hybridization rate between hawthorn and apple maggot flies and there are no post zygotic barriers that have been observed Apple trees and hawthorn trees have fruit hat ripen at different times of year which leads to temporal separation of apple and hawthorn flies Questions 1 Based on your initial reaction are these flies two species No they are the same species they are just born and raised within different environments 2 Which information is relevant to the morphological species definition choose all that apply a Hawthorn and apple maggot flies are physically indistinguishable b There is a 4 6 hybridization rate between hawthorn and apple maggot flies c Hawthorn and apple maggot flies are genetically distinguishable and have a d Hawthorn and apple maggot flies strongly prefer to mate and lay fertilized eggs in distinct genetic profiles hawthorns and apples respectively 3 According to the morphological species concept are hawthorn and apple maggot flies separate species Explain They technically are because they prefer to breed with their own maggots that were raised within their environment and they have genetic differences 4 Which information is relevant to the biological species definition choose all that apply a Hawthorn and apple maggot flies are physically indistinguishable b There is a 4 6 hybridization rate between hawthorn and apple maggot flies c Hawthorn and apple maggot flies are genetically distinguishable and have a d Hawthorn and apple maggot flies strongly prefer to mate and lay fertilized eggs in distinct genetic profiles hawthorns and apples respectively 5 What reproductive barrier limits interbreeding between hawthorn and apple maggot flies The fruit that they breed in 6 According to the biological species concept are hawthorn and apple maggot flies separate species Explain Technically yes because they mate within their respective fruit 7 Based on the information provided in this case study are hawthorn and apple maggot flies separate species Explain your thoughts Which species concept are you using By the biological concept their reproductive behavior is different therefore they are different The mating within their respective fruit separates them and they can also create hybrids while the Hawthorne flies cannot 8 Is this an example of allopatric speciation or sympatric speciation Explain your reasoning Sympatric speciation because they are within the same vicinity but it is there reproductive behavior or their sexual selection to reproduce with flies that are like them that separates them