3.2: origins of biodiversity

Question 1

biodiversity arises from evolutionary processes -

Answer 1

niological variation arises randomly and can either be beneficial to, damaging to, or have no impact on, the survival of the individual

Question 2

natural selection:

Answer 2

in any environment, the individuals that have the best adaptive features are the ones most likely to survive and reproduce - ‘survival of the fittest’

resulting in natural selection:
- individuals in a species show a range of variation caused by differences in genes
- when organisms reproduce, they produce more offspring than the environment is able to support
- this leads to competition for food and other resources which results in a ‘struggle for survival’
- individuals with characteristics most suited to the environment have a higher chance of survival and more chances to reproduce
- therefore the genes resulting in these characteristics are passed on to their offspring at a higher rate than those with characteristics less suited to survival
- this means that in the next generation, there will be a greater number of individuals with the better adapted variations in characteristics

Question 3

speciation:

Answer 3

the formation of new species when populations of a species become isolated and evolve differently from other populations.

depends on:
isolation of species: the process by which two populations become separated by
- change of environment
- change of gene pool

leading to the species adapting over time and thus speciation. for eg. a giraffe with a slightly longer neck will be able to reach leaves that others can not.

Question 4

isolation factors leading to speciation -

Answer 4

geographical factors: island formation, loss of land bridges and mountain ranges

behavioural factors: reproductive displays, songs, daily activity

genetic factors: inability to produce fertile offspring due to genetic differences

reproductive factors: anatomical differences especially in reproductive organs

Question 7

eg. of speciation -

Answer 7

when Arizona’s Grand Canyon formed, squirrels and other small mammals that had once been part of a single population could no longer contact and reproduce with each other across this new geographic barrier. they could no longer interbreed. the squirrel population underwent allopatric speciation.

today, two separate squirrel species inhabit the north and south rims of the canyon. on the other hand, birds and other species that could easily cross this barrier continued to interbreed and were not divided into separate populations.

Question 8

evolutionary consequences of tectonic plate movement -

Answer 8

has had a profound impact on the evolution of life on Earth. it has led to the creation of land bridges and physical barriers, and the changing distribution of continents has affected climate and food supply

Question 9

land bridges & physical barriers -

Answer 9

tectonic plate movement has led to the creation of land bridges, which connect previously isolated landmasses and allow for the movement of organisms between them
for eg. the Bering land bridge connected Asia and North America during the last ice age, allowing for the migration of animals such as mammoths and humans.

similarly, the formation of the Isthmus of Panama created a physical barrier between the Atlantic and Pacific Oceans, leading to the evolution of distinct marine species on either side.

Question 10

climate & food supply -

Answer 10

the distribution of continents has also had a significant impact on climate and food supply, which has contributed to evolution.
for eg. the separation of Africa and South America led to the formation of the Atlantic Ocean, which created a drier climate in Africa due to reduced moisture transport. this led to the evolution of savannah ecosystems and the expansion of grassland habitats, which in turn influenced the evolution of grazing animals such as antelopes and zebras

similarly, the movement of Antarctica to its current position has led to the formation of the Antarctic Circumpolar Current, which has had a major impact on global ocean currents and climate

Question 11

genetic isolation -

Answer 11

tectonic plate movement has also led to the genetic isolation of populations, which can lead to the formation of new species over time

for eg. the separation of Australia from the rest of the Gondwana supercontinent led to the evolution of unique flora and fauna, such as the marsupials and eucalyptus trees, that are found only in Australia