Adaption, Variation, Natural Selection Pt.2 Flashcards
What are homologous structures?
Similar structural elements that may have a different function
Homologous structures indicate evolutionary relationships among species.
What are analogous structures?
Structures that perform similar functions but do not have a common evolutionary origin
Analogous structures arise due to convergent evolution.
What are vestigial structures?
Structures present in modern organisms that serve no purpose
Examples include the human appendix and whale pelvis.
What did scientists notice about embryos in the 1800s?
Striking similarity between embryos of different species
This observation led to insights about evolutionary relationships.
What does ‘ontogeny recapitulates phylogeny’ mean?
An organism shows its evolutionary history through its embryology
This concept suggests that developmental stages reflect evolutionary ancestry.
What is the relationship between related organisms and developmental stages?
The more closely related organisms are, the more their developmental stages will resemble each other
This is observed in various species like bats, birds, and dragonflies.
What is a significant similarity shared by all organisms?
Similar DNA and proteins
This commonality suggests a shared ancestry among all life forms.
What is the significance of genetic similarity between species?
The closer related organisms are, the more similar their DNA sequences
For example, humans and chimpanzees share 98.5% of their DNA.
How genetically similar are humans and chimpanzees?
98.5% homologous
This high percentage indicates a close evolutionary relationship.
What percentage of genetic similarity do all humans share?
100%
While all humans have the same genes, sequence differences make each person unique.
What percentage of genetic similarity do chimpanzees share with humans?
98%
Chimpanzees are the closest living relatives to humans.
What percentage of genetic similarity do mice share with humans?
92%
This high similarity highlights the genetic closeness of mammals.
What percentage of genetic similarity do fruit flies share with humans?
44%
Research on fruit flies has provided insights into genetic functions applicable to both insects and mammals.
What percentage of genetic similarity do yeasts share with humans?
26%
Yeasts have many housekeeping genes similar to those in humans.
What is the genetic similarity percentage between thale cress weed and humans?
18%
Despite significant metabolic differences, some similarities exist in housekeeping genes.
What is phylogeny?
The evolution of a species or group, especially in reference to lines of descent and relationships among organisms
Phylogenetic trees visually represent these evolutionary relationships.
How can evolutionary branching be depicted?
In a tree
Phylogenetic trees illustrate the connections between different species.
What is a hypothetical common ancestor?
An ancestral organism from which multiple species have descended
This concept is fundamental to understanding evolutionary biology.
What is a character change in phylogenetics?
A change inherited by a species that can indicate evolutionary relationships
Such changes help in constructing phylogenetic trees.
What is speciation?
Formation of a new species through natural selection.
What are the pathways for generating new species?
- Transformation
- Divergence
What is transformation in the context of speciation?
One species gradually changes into another by which it is replaced.
What is divergence in speciation?
One or more species arise from a parent species that continues to exist.
What is required for speciation to occur?
Barriers that cause a group of individuals of the same species to be isolated from the rest.
What are geographical barriers?
Barriers such as rivers and mountains that can divide populations.
How do geographical barriers affect populations?
Populations on each side of the barrier will evolve independently.
What are biological barriers?
Factors that keep individuals reproductively isolated even when ranges overlap.
Give examples of biological barriers.
- Different mating calls
- Dances
- Pheromones
- Habitats
- Breeding times/seasons
- Mechanical barriers
What is the simplified summary of how speciation occurs?
- Population is separated by a physical or behavioural barrier
- No longer sharing mutations
- Natural selection works on separated groups
- Accumulated differences lead to two distinct species.
What is reproductive isolation?
Occurs when genetic variation allows individuals to exploit different resources.
What is adaptive radiation?
Diversification of a common species into a variety of species, all of which are differently adapted.
What is the pace of evolution characterized by slow, steady, linear change over time?
Gradualism
Gradualism refers to the theory that evolution occurs slowly and gradually over long periods.
What is punctuated equilibrium?
Long periods of equilibrium interrupted by ‘rapid’ periods of speciation
Punctuated equilibrium suggests that species remain relatively unchanged for long periods, with rapid changes occurring during speciation events.
What summarizes the evolution by natural selection?
- Life forms have developed from ancestral species
- All living things are related by varying degrees
- All living things on Earth have a common origin
- Speciation requires random heritable genetic mutations
These points outline the fundamental concepts of evolution by natural selection.
What is required for speciation?
Random heritable genetic mutations
Speciation occurs when these mutations provide a selective advantage, allowing individuals with these traits to survive and reproduce.
True or False: All living things on Earth have a common origin.
True
This concept is integral to the theory of evolution, indicating a shared ancestry among all life forms.
Fill in the blank: __________ requires random heritable genetic mutations.
Speciation
Speciation is the process by which new species arise, often facilitated by genetic changes.
