Module 4.3
Formation of new species
Glossary:
All words with ‘*’ can be found below, however, some definitions are found within the
text
Species: A group of organisms that closely resemble each other and are able to breed
among themselves (not with any other species) and produce offspring
Population: A group of individuals of the same species occupying a particular habitat
Founder effect: Refers to the loss of genetic variation when a very small number of
individuals from a larger population to establish a new colony
Convergent evolution: Process during which species are not closely related to each
other independently evolve similar kind of traits to adapt to similar
environments/ecological niches
Divergent evolution: Process in which a trait held by a common ancestor evolves into
different variations over time
Extinction: Permanent loss of all members of a species
Speciation: The evolutionary formation of new species that are genetically distinct from
the older, parental species
Geographic (allopatric) speciation: Speciation due to part of the population becoming
isolated from the ancestral species
Sympatric speciation: Speciation that occurs when a new species arises in the same
area as the ancestral species without any geographical isolation
Endemic: Unique to a certain area
Reproductive isolation: A mechanism that prevents two or more species from
exchanging genes (interbreeding) and producing viable, fertile hybrids even though they
are not geographically separated
Pre/post-zygotically: Pre/post mating
Stridulating: To make a chirping or grating sound by rubbing certain parts of the body
together
Natural selection:
, ● It is caused by genetic variation within a population which can influence the
nature of the offspring
Causes of variation in individuals in a species:
1. Sexual reproduction
● Meiosis - during meiosis there is a rearrangement/shuffling of the genetic
material, this includes:
○ The random arrangement of homologous chromosomes on the
equator of the cell
○ Crossing over when bivalents form
● Chance fertilisation
○ During fertilization, the genetic material from the female and male
gametes recombine
○ No choice as to whether male gamete will fuse with the female
gamete
○ As a result = variety of genotypes (genotypic combinations) are
formed in the offspring
○ The altered genotypes may or may not appear in the phenotype
● Random mating
○ This means that every female gamete (with her particular genotype)
has an equal chance to be fertilised by every male gamete (with its
particular genotype) in the population
2. Mutations- any sudden alteration in the genetic makeup/genetic code of an
organism
● While mutations can occur in somatic and gametic cells in biological
evolution we are only interested in this section in gametic mutations
● Gametic mutations occur in gametes and can give rise to offspring that
carry the mutation in all of its cells (aka germ-line mutations) can be
passed onto the offspring and have a strong influence on evolution
○ Changes in base sequences of DNA
- This is the main way alleles are created and is the main
source of genetic variation
○ Whole chromosomes may be deleted or duplicated, and even the
entire chromosomal complement can multiply in a process called
polyploidy
● A small percentage of mutations can be beneficial = results in changes in
the phenotype
Formation of new species
Glossary:
All words with ‘*’ can be found below, however, some definitions are found within the
text
Species: A group of organisms that closely resemble each other and are able to breed
among themselves (not with any other species) and produce offspring
Population: A group of individuals of the same species occupying a particular habitat
Founder effect: Refers to the loss of genetic variation when a very small number of
individuals from a larger population to establish a new colony
Convergent evolution: Process during which species are not closely related to each
other independently evolve similar kind of traits to adapt to similar
environments/ecological niches
Divergent evolution: Process in which a trait held by a common ancestor evolves into
different variations over time
Extinction: Permanent loss of all members of a species
Speciation: The evolutionary formation of new species that are genetically distinct from
the older, parental species
Geographic (allopatric) speciation: Speciation due to part of the population becoming
isolated from the ancestral species
Sympatric speciation: Speciation that occurs when a new species arises in the same
area as the ancestral species without any geographical isolation
Endemic: Unique to a certain area
Reproductive isolation: A mechanism that prevents two or more species from
exchanging genes (interbreeding) and producing viable, fertile hybrids even though they
are not geographically separated
Pre/post-zygotically: Pre/post mating
Stridulating: To make a chirping or grating sound by rubbing certain parts of the body
together
Natural selection:
, ● It is caused by genetic variation within a population which can influence the
nature of the offspring
Causes of variation in individuals in a species:
1. Sexual reproduction
● Meiosis - during meiosis there is a rearrangement/shuffling of the genetic
material, this includes:
○ The random arrangement of homologous chromosomes on the
equator of the cell
○ Crossing over when bivalents form
● Chance fertilisation
○ During fertilization, the genetic material from the female and male
gametes recombine
○ No choice as to whether male gamete will fuse with the female
gamete
○ As a result = variety of genotypes (genotypic combinations) are
formed in the offspring
○ The altered genotypes may or may not appear in the phenotype
● Random mating
○ This means that every female gamete (with her particular genotype)
has an equal chance to be fertilised by every male gamete (with its
particular genotype) in the population
2. Mutations- any sudden alteration in the genetic makeup/genetic code of an
organism
● While mutations can occur in somatic and gametic cells in biological
evolution we are only interested in this section in gametic mutations
● Gametic mutations occur in gametes and can give rise to offspring that
carry the mutation in all of its cells (aka germ-line mutations) can be
passed onto the offspring and have a strong influence on evolution
○ Changes in base sequences of DNA
- This is the main way alleles are created and is the main
source of genetic variation
○ Whole chromosomes may be deleted or duplicated, and even the
entire chromosomal complement can multiply in a process called
polyploidy
● A small percentage of mutations can be beneficial = results in changes in
the phenotype
