A4.1 - Evolution of Speciation

What is speciation?

Speciation is the evolutionary process by which new biological species arise. It occurs when populations of a species become reproductively isolated from each other to the extent that they can no longer interbreed and produce viable, fertile offspring.

What is divergent evolution?

refers to the process by which closely related species evolve different traits and characteristics over time. This divergence occurs when populations of a common ancestor become isolated in different environments or face different selective pressures, leading to the accumulation of distinct adaptations.

What is reproductive isolation?

refers to the situation in which two populations of organisms are prevented from interbreeding and producing viable, fertile offspring. This isolation can occur due to various mechanisms and barriers, leading to the divergence of populations and, ultimately, the formation of new species.

What are homologous structures?

Homologous structures are anatomical features that are similar in structure and position but may serve different functions in different organisms. These structures are derived from a common ancestor and have a similar underlying structure, despite possibly having different functions due to evolutionary adaptation to different environments or ecological niches.

What is convergent evolution?

Convergent evolution is the process by which unrelated or distantly related organisms independently evolve similar traits, characteristics, or adaptations in response to similar environmental pressures or ecological niches. Despite not sharing a recent common ancestor, these organisms evolve analogous structures or behaviors that serve similar functions due to similar selective pressures.

What is a vestigial structure?

an anatomical feature or organ that has reduced in size, complexity, or function over the course of evolution. These structures are remnants of organs or traits that were fully functional in the organism's ancestors but are no longer essential or functional in the organism's current form or way of life.

What is selective breeding?

also known as artificial selection, is the process of intentionally breeding organisms with desirable traits to produce offspring with those same traits or traits that are further enhanced.

What is adaptive radiation?

When a group of individuals from a population migrates to a new area, they often occupy vacant ecological niches

What are the two types of speciation?

Allopatric - Meaning “Different homeland”

Sympatric - Meaning “Same homeland”

what are 4 examples of sympatric speciation

1. Behavioral habits (eating habits, mating behaviors, etc)

2. Temporal differences (different groups mating a different times)

3. Mechanical isolation (Anatomical structures, such as size prevent interbreeding)

4. Chemical isolation (chemical barriers prevent fertilization)

Where can evidence for evolution be found?

Evidence from:

• nucleic acids

• gene families

• selective breeding

• homologous structures

• fossils

• fossil records

Define evolution

The cumulative change in the heritable characteristics of a population over time.

What is natural selection

When some organisms in a population become more likely to survive because they posses the favourable traits. They then pass on their genes as a result of having those traits to their offsprings. Organisms that do not have the favourable traits will most likely die off. sources of variation that allow such changes to happen include hybridization, miosis, and random sexual reproduction.

What is the evidence of evolution from nucleic acids?

A change in heritable characteristics requires a change in genes. Evidence of this can be seen when comparing the base sequences and the same gene in different species. The more closely related the organisms is, the fewer the differences in the base sequence.

What is the evidence of evolution from gene families?

Conservation of families of genes can be seen across diverse groups of organisms. A variant of the Hox gene family is found in all animals with a clear head-to-tail axis.

What is the evidence of evolution from Selective breeding?

it provides evidence for evolution as targeted breeds can show significant variation in a short period.

What is the evidence of evolution from homologous structures

The more similar the homologous structures are between two species, the more closely related they are likely to be. Homologous structures illustrate adaptive radiation which is the evolutionary explanation that different species has the same common ancestor. An example of a homologous structure would be a rudimentary organ, such as an appendix.

What is the evidence of evolution from fossils

the age of a fossil can be determined by the rock strata and using radioisotope dating

What is the evidence of evolution from fossil records

1. The sequence in fossils matches the sequence in which they are expected to evolve.

2. The sequence of fossils fits the ecology of the groups.

3. Sequences of fossils link existing organisms to their likely ancestors.

What are the requirements for speciation

Reproductive isolation and differential selection

What is reproductive isolation?

If two reproductive populations are split into separate species, they can not be allowed to interbreed. Prevention of gene flow is often the consequence of geographical separation

What is differential selection

Differential selection is when individuals with certain traits survive and reproduce more successfully than others because of their advantages in a particular environment. This process leads to changes in the frequency of these traits within a population over time.

What is adaptive radiation?

when one species rapidly evolves into many diverse species, each suited to different environments or ecological niches.