4.3, 4.4 Adaptation and Evolution Flashcards
4.3 Understand the concept of niche and be able to discuss examples of adaptation of organisms to their environment (behavioural, physiological and anatomical). 4.4 Understand how natural selection can lead to adaptation and evolution.
What is a niche?
the role of an organism within its habitat and the way it exploits its environment, including its interactions with other living organisms and its interactions with the non-living environment
e.g. What is frogs niche in its environment?
- eating insects and being eaten by a bird
- breathing in oxygen and breathing out carbon dioxide
- occupying and interacting with the pond and being active throughout the day
- etc.
Explain why a niche can only be occupied by one species:
- every species has its own unique niche
- this is because if two species try to occupy the same niche, competition occurs and the more successful species will win
- only one species will be left as the other species dies out
Why do some species look like they are filling the same niche?
- niches can be very similar, but are always slightly different
- e.g. even if two species eat the same food and live in the same habitat, they could be active at different times so are not occupying the same niche
What is an adaptation?
a feature that increases an organism’s chance of survival and reproduction
What are behavioural adaptations?
actions by organisms that help them survive and reproduce
What is an example of a behavioural adaptation?
e.g. possums play dead to avoid attacks from predators
e.g. scorpions dance to attract mates
What are anatomical adaptations?
features/structures we can observe or dissect that help an organism survive and reproduce
What is an example of an anatomical adaptation?
e.g. whales have blubber to keep them warm in cold water
e.g. turtles have shells to protect them from predators/the environment
What are physiological adaptations?
internal processes of an organism that helps them survive and reproduce
What is an example of a physiological adaptation?
e.g. thermophilic bacteria can tolerate very high temperatures, allowing them to live in thermal vents
e.g. some bacteria produce antibiotics that kill other bacteria, reducing competition
What is natural selection?
the process by which individuals who are better adapted (fitter) are more likely to survive, reproduce, and pass on their alleles to their offspring, leading to the increase in the frequency of advantageous alleles over time and generations
What is evolution?
a change in allele frequency in a population over time (generations)
How does natural selection lead to evolution?
- there is naturally occurring genetic variation within a population as new alleles can be introduced through mutations
- a change in the environment causes a change in the selection pressures acting on the population (e.g. outbreak of disease)
- some alleles determine characteristics that make an individual more likely to survive and reproduce (e.g. immunity)
- those alleles that were previously selectively neutral now have a selective advantage
- this means that those with the advantageous alleles are more likely to survive, reproduce, and pass on their alleles to offspring
- over time, more and more offspring inherit the advantageous alleles
- this means that evolution has occurred, as there has been a change in the allele frequency of a population (with the frequency of the advantageous alleles increasing)
What is adaptation?
the process of change by which an organism or species becomes better suited to its environment by developing features that increase its chance of survival and reproduction
How does natural selection lead to adaptation?
- there is naturally occurring genetic variation in a population as new alleles can be introduced through mutations
- therefore there is variation in the phenotypes and characteristics of the population
- a change in the environment causes a change in the selection pressures acting on the population (e.g. outbreak of disease)
- some individuals have alleles that determine advantageous characteristics (e.g. have immunity)
- this means that they are better adapted and are more likely to survive, reproduce, and pass on their advantageous alleles to offspring - these adaptations give a selective advantage
- over time, more and more offspring inherit the advantageous alleles and allele frequency changes
- this means that adaptation has occurred, as the favourable adaptations have become more common and more individuals are better adapted to the environment
What is a selection pressure?
something that affects an organism’s chance of survival and reproduction
List 7 examples of selection pressure:
- predation
- environmental conditions (e.g. dry climate)
- competition for food
- competition for habitats and space
- competition for mates
- disease
- direct human influence (e.g. deforestation)
Explain the terms selectively neutral, selective advantage, and selective disadvantage:
- selectively neutral: has no advantage or disadvantage in terms of survival and reproduction
- selective advantage: increases the chance of survival and reproduction, and hence is more likely to be passed on to offspring (is selected for)
- selective disadvantage: decreases the chance of survival and reproduction, and hence is less likely to be passed on to offspring (is selected against)
What happens to the individuals who don’t have the advantageous alleles during natural selection and how does this benefit those who do?
- those without die out
- so overall there are fewer individuals and less competition for resources
Who came up with the theory of evolution by natural selection?
Charles Darwin
