A4.1 - Evolution and Speciation

Change in Gene Pool of a population over generations over time

natural selections
Gene flow
mutation
non random mating
Genetic drift

chance events that shrink the gene pool. Smaller gene pool may not reflect orginal larger gene pool

migration in and out of the population that changes the alles in the gene pool

total amount of genes in a group

Evolution through use and disuse; acquired traits are inherited.
The environment causes changes in traits.
All acquired traits are inherited.
Changes occur in response to needs.
Evolution is goal-oriented (towards perfection)

evolution through natural selection; favorable treats are inherited based on survial and reproduction
The environment selects for existing traits.
Variations exist randomly before selection.
Evolution has no specific goal.

1. Belief in Evolution: Both proposed that species change over time.
2. Adaptation to Environment: Both recognized that organisms adapt to their environments.
3. Gradual Change: Evolution occurs gradually over long periods.
4. Inheritance of Traits: Both believed traits were passed to offspring.

random alterations is the genetic code that can change during DNA replication, Change the DNA sequance and intern may affect the Amino Acids sequances for protein

--Similar--
Homologous Sequences: Similarities in DNA, RNA, and amino acid sequences between different species can indicate a common evolutionary ancestry. These homologous sequences suggest that different species share a common genetic heritage.

Genetic Code Universality: The genetic code used to translate DNA and RNA sequences into amino acids is nearly universal among all life forms. This universality of the genetic code provides strong evidence for a common ancestor and shared evolutionary history.

--Difference--
Divergence: Differences in DNA and RNA sequences among species can highlight the genetic changes that have occurred over evolutionary time. These differences are often due to mutations and other genetic modifications.

Functional Diversity: While DNA and RNA serve as the genetic material and play various roles in gene expression, amino acid sequences are involved in the formation of proteins. Variations in amino acid sequences can result in the evolution of different protein functions and structures.

Functional Significance: Differences in DNA, RNA, and amino acid sequences can lead to changes in an organism's traits and characteristics. These changes, when advantageous, can become fixed in a population over time through natural selection.

Molecular clocks are used to estimate evolutionary divergence by comparing DNA or amino acid sequences. DNA and protein sequences evolve at a constant rate of change overtime

1. Non-coding DNA: provides the best means of comparison as mutations will occur more readily in these sequences

2. Gene sequences: mutate at a slower rate, as changes to base sequence may potentially affect protein structure and function

3. Amino acid sequences: also used for comparison, slowest rate of change due to codon degeneracy

What is hemoglobin?
Hemoglobin is a protein in red blood cells that carries oxygen from the lungs to the rest of the body (NHI).

Hemoglobin in Vertebrates:
There is larger Hb gene (hemoglobin gene) supply in shallow water due to its more variable environment (Nature).

Adaptation of the Hb Gene:
There has been evidence that found that the Hb gene varied from 5 to 9 in current-day codfish. Compared to ancient/ancestral codfish, who had only 5 Hb genes, there is a pattern of evolution (Nature).

Chromosome found inside of the mitochondria
Passed down from maternal parent
Mitochondrial DNA can be past down from maternal parent which makes it easier to trace lineage more easily than RNA

Evidence from RNA: RNA is the product of transcription, RNA base sequence provides information about the DNA base sequences of genes that are expressed in a cell.

Ribosomal RNA sequences are highly conserved across species, and small differences can show evolutionary relationships, with fewer differences indicating closer relatedness.

Cytochrome c- mitochondrial proteins
key participant in the life-supporting function of ATP synthesis
Their sequence is similar to produce ATP (ATP is necessary for cells to live)
By comparing the order of amino acids that make up the protein Cytochrome C and noting the differences in the arrangement, scientists can infer relationships among species

humans intentionally select organisms with certain traits to reproduce.

Improved Traits: Selective breeding allows humans to enhance desirable traits such as size, productivity, and disease resistance in both animals and crops.

Agricultural Productivity: Enhanced crop varieties and livestock breeds can increase agricultural productivity, leading to higher yields and food security.

Economic Gain: Selectively breeding animals and crops that yield more valuable products, such as high-quality meat, milk, or wool, can result in economic benefits for farmers and producers.

Disease Resistance: Breeding for disease resistance in both plants and animals can help reduce losses and the need for chemical treatments.

Adaptation to Local Conditions: Tailoring plant and animal varieties to local environmental conditions, like climate or soil type, can optimize production and resource utilization.

The process begins with the identification of desirable traits or characteristics in a population. These traits are chosen for their potential advantages, such as increased yield, disease resistance, or other valuable features.

Breeding Pair Selection:
Individuals that exhibit the desired traits are chosen as breeding pairs. These individuals will produce the next generation. By selecting specific parents with these traits, the offspring are more likely to inherit and express them.

Reproductive Isolation:
To focus the genetic changes, individuals with other traits are often excluded from the breeding process. This prevents the mixing of unwanted genes.

Generation Repetition:
The selective breeding process is repeated over multiple generations. Each time, individuals with the target traits are chosen for breeding. The resulting offspring inherit and accumulate these traits.

Maize (corn) was domesticated from teosinte, a wild grass in southern Mexico, around 9,000 years ago, leading to less stalks, larger kernels and cobs

dogs were domesticated 14,000 years ago from a gray wolf ancestory
humans selected dogs with particular traits or behaviors that suited their needs, such as hunting, herding, guarding, or companionship. For example, early humans might have preferred dogs that excelled in hunting as their companions.

anatomical features in different species that share a common evolutionary origin but may serve different functions.

Bat wings and cat paws are an example of homologous structures because they share the common ancestry.
Overtime they have changed through the divergent evolution, but they are still able to be linked to the common ancestor
This can be seen in the similar constructions of the bat wing and cat paw
But they have different functions - bat wings for flying and cat paws for walking

A limb with five digits such as a human hand or foot which are found in many amphibia, reptiles, birds and animals

the same function but different evolutionary origins.

unrelated species evolve similar traits independently, often due to adapting to similar environments or ecological niches.
Unlike homologous structures, these similarities arise without a common evolutionary ancestor

similar structures adapt to different environments or tasks.

a population of one species diverges to become two distinct species

Species increases number of species
Exintciton deacreases number of species

Physical barrier = unable to mate with species on the otherside of the barrier

reproductive isolation
differential selection

more or less resources
climate
predators
food sources

they are both primates from the genus Pan. They are geographically isolated from each other by the Congo river
• An example of a speciation event that has resulted from geographical isolation is the evolution of bonobos (Pan paniscus) and chimpanzees (Pan troglodytes)
• Chimpanzees are found to the north of the Congo river, and bonobos to the south
• This suggests that at some point in their evolutionary past the river caused two populations of their ancestor species to become geographically isolated
• Different selection pressures would have acted on the two populations, so differential selection occurred, resulting in differences between the two populations
E.g:
• Chimpanzees tend to be more behaviourally aggressive than bonobos; this could have arisen due to more intense competition for resources
• Chimpanzees have male-dominated social structures while bonobos have dominant females
• Eventually the two groups became reproductively isolated, and were two separate species