A4.1 Evolution and speciation Flashcards
Define the term evolution.
Evolution refers to changes in the heritable characteristics of a population.
Define the term heritable.
The term heritable is used to describe features that can be passed from parents to offspring; heritable characteristics are controlled by genes.
Lamarck’s theory of evolution states that populations evolve when ________________________ are passed onto __________.
Lamarck’s theory of evolution states that populations evolve when acquired characteristics are passed on to offspring.
What is the difference between Darwin’s and Lamarck’s theories of evolution?
The difference between Darwin’s and Lamarck’s theories is that Darwin describes the passing on of advantageous characteristics that exist from birth (i.e. features that are genetically determined) while Lamarck describes the passing on of advantageous characteristics that are acquired during an organism’s lifetime.
True or False?
Advantageous characteristics that arise during an organism’s lifetime cannot be described as evolution.
True.
Evolution involves changes in heritable characteristics, so cannot be acquired during an organism’s lifetime.
Why is the theory of evolution unlikely to ever be falsified? (NOS)
The theory of evolution is unlikely to ever be falsified because it explains many scientific observations and is supported by many different types of evidence. Any new evidence that does not fit the existing theory may result in changes to the theory rather than falsification.
True or False?
The theory of evolution will eventually be formally proved. (NOS)
False.
The theory of evolution is not a mathematical formula that can be proved; the nature of the scientific method means that this type of proof is not possible in this instance.
The theory of evolution is considered to be empirically true on the basis of observation and measurement, and is not awaiting more evidence before it is scientifically accepted.
What are three sources of sequence data?
Sources of sequence data include:
DNA
RNA
proteins
Define the term common ancestor.
A common ancestor is an ancestral individual from which two or more individuals descend, e.g. the common ancestor of two cousins would be their grandparents. The term can also be used to describe an ancestral species.
What does a high similarity in DNA base sequences between species indicate?
A high similarity in DNA base sequences between species indicates that they are close evolutionary relatives that share a recent common ancestor.
True or False?
Comparing the sequences of proteins that are present in many different species can yield useful information about evolutionary relationships.
True.
Comparing amino acid sequences of proteins that are present in many species allows the evolutionary relationships between all of the many species to be studied.
Studying a protein that is unique to a few species will only allow assessment of the relationship between those few species.
Define the term selective breeding.
Selective breeding is the process during which humans choose organisms with desirable characteristics and breed them together repeatedly to increase the expression of these characteristics over many generations.
What is the difference between natural selection and selective breeding?
The difference between natural selection and selective breeding is that:
in selective breeding humans decide which characteristics are desirable and which individuals will breed
in natural selection survival and reproduction are determined by environmental factors
How does selective breeding in domestic animals and crop varieties provide evidence for evolution?
Selective breeding in domestic animals and crop varieties provides evidence for evolution because of the variation that is generated by this process. This variation arises due to the accumulation of genetic differences, just as heritable changes occur in natural selection.
Define the term homologous structure.
Homologous structures are body parts that look and function differently but that share structural similarities. The presence of such structures indicates common ancestry.
True or False?
The human foot, whale flippers and bird wings are examples of pentadactyl limbs.
True.
The human foot, whale flippers, and bird wings are examples of pentadactyl limbs.
How does the pentadactyl limb provide evidence for evolution?
The pentadactyl limb provides evidence for evolution because it is a homologous structure that often differs in form and function but that is structurally similar across species; this indicates that all of these species evolved from a common ancestor.
What is an analogous structure?
Analogous structures are characteristics with similar form and function, but with different evolutionary origins.
What is convergent evolution?
Convergent evolution is the process by which distantly related species independently evolve similar traits as a result of adapting to similar environments or ecological niches.
What causes convergent evolution to occur?
Convergent evolution occurs when two distantly related species live in habitats with similar selection pressures, leading to the passing on of similar advantageous characteristics.
True or False?
Analogous structures provide evidence of shared ancestry.
False.
Analogous structures indicate that two species have evolved in response to similar selection pressures and do not indicate recent shared ancestry.
It is homologous structures that indicate shared ancestry.
True or False?
The presence of streamlined shape in dolphins (a mammal) and sharks (a fish) is an example of convergent evolution.
True.
Dolphins and sharks are both aquatic animals that have evolved to move efficiently in water. Their similarity in body shape does not indicate shared recent common ancestry.
Define the term speciation.
Speciation is the development of new species that occurs when a pre-existing species is split.
True or False?
Speciation increases diversity.
True.
Speciation gives rise to new species, so increases diversity.
