✓Chapter 8.6 Types of Evolution: Divergent Versus Convergent ✓ Flashcards
(22 cards)
What is divergent evolution?
Closesly related species start with a common ancestor but after living in different environments, develop different traits over time, eventually becoming so different that they form a new species.
What causes populations to diverge in divergent evolution?
-Isolation which stops gene flow.
-Isolation can be caused by physical barriers (e.g. mountains or rivers) or changes in reproduction.
-Over time, each group adapts to its own environment, leading to differences that may eventually result in new species
How do homologous structures support the idea of divergent evolution?
Homologous structures support the idea of divergent evolution by showing that different species have body parts with the sam esturtcure but different functions, suggesting they all came from a common ancestor and evolved differently to suit their environment
What is adaptive radiation?
The process by which a species rapidly diversifies into many taxa with differing adaptations
How are koalas, Tasmanian devils, and marsupial moles an example of adaptive radiation?
They share a common marsupial ancestor but developed very different dentition (teeth) suited to different diets, due to adaptation to different ecological niches.
How do koala teeth reflect their diet?
Koalas have complex molars with cutting blades, adapted for chewing eucalyptus leaves.
How do Tasmanian devil teeth reflect their diet?
They have long, sharp incisors and strong molars for tearing meat and crushing bones.
How are marsupial mole teeth adapted to their diet?
Their degenerate, conical teeth are suited to an insectivorous diet, with large premolars and variable incisors/canines.
What environmental changes triggered adaptive radiation in Australia’s past?
During the Middle Miocene epoch, central Australia had lush forests and waterways, allowing for a wide range of marsupials to adapt and diversify.
What happened during the Pliocene epoch that affected Australian species?
The climate became drier, tropical forests retreated, and grasslands replaced them, causing some species to go extinct and others (like kangaroos and wallabies) to radiate into new niches.
What is an example of a species group that could not survive the environmental changes in Australia?
Diprotodontids and some possums could not adapt to the loss of forest habitat and became extinct.
What is convergent evolution?
Convergent evolution is a pattern where distantly related organisms independently evolve similar adaptations due to living in similar environments.
What drives convergent evolution?
Similar environmental pressures cause unrelated species to develop similar features that help them survive in that environment.
What is an example of convergent evolution involving ant-eating animals?
Echidnas, numbats, and pangolins have independently evolved long snouts, extendable tongues, and digging claws to eat ants and termites, despite being from different orders.
Why are anteaters like echidnas and pangolins not considered closely related?
They belong to different evolutionary lineages and do not share a recent common ancestor, but they evolved similar traits due to similar diets and habitats.
What are analogous structures?
Analogous structures are features that perform similar functions but evolved independently in unrelated species, often due to convergent evolution.
How do dolphins and sharks demonstrate convergent evolution?
Dolphins (mammals) and sharks (fish) both have streamlined bodies and fins adapted for swimming, due to living in similar aquatic environments, not because of close ancestry.
Why do analogous structures arise?
They arise as solutions to similar environmental challenges, not from shared ancestry.
Define divergent evolution and give an example of evidence for it in the evolution of species.
-Divergent evolution is the process by which two or more related species become increasingly different from a common ancestor due to different environmental pressures or isolation
-An example of evidence for divergent evolution is homologous structures, such as the differing dentition (teeth) of koalas, Tasmanian devils, and marsupial moles.
-These species share a recent marsupial ancestor but have evolved distinct teeth adapted to different diets, showing how species diverge over time.
Define convergent evolution and give an example of evidence for it in the evolution of species.
-Convergent evolution is when distantly related species independently evolve similar traits as a result of adapting to similar environments or ecological roles.
-An example is the development of similar ant-eating adaptations in echidnas, numbats, and pangolins.
-These mammals are not closely related but all evolved elongated snouts, long tongues, and strong claws for consuming ants and termites.
-Their similarities are due to environmental pressures rather than shared ancestry.
Classify the pentadactyl limb as homologous or analogous and give a reason why.
The pentadactyl limb is a homologous structure. This is because it has the same basic underlying structure—five digits in a limb—even though it is adapted for different functions in different species (e.g. grasping in humans, flying in bats, and swimming in whales). Its similarity in structure across species indicates a common ancestor.
Explain the importance of using both living and fossil forms in constructing phylogenies.
Using both living and fossil forms in phylogenetic trees allows scientists to trace evolutionary relationships more accurately.
-Fossils provide direct evidence of ancestral species and when certain traits first appeared.
Living organisms provide genetic and morphological data that can be compared to fossil forms. Together, they offer a more complete picture of how species have evolved over time and help identify extinct lineages and transitional forms.
