Bio U1

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Morphological species are groups of individuals who are morphologically similar (similar traits) to each other and morphologically different from other species.

Species are organisms with groups of shared or similar traits. (Linnaeus definition from the morphological species concept)

The biological species concept has replaced the morphological species concept.

A species is a group of organisms capable of reproducing with each other to produce fertile offspring (new definition based on the biological species concept). Linnaeus created binomial nomenclature.

All organisms are given a scientific name based on the Linnaeus system: ★ All members of the same genus share similar traits and are closely related ★ Species aren’t descriptive to their groups

★ Scientific names are always italicized or underlined.

Level of organization:

1. Domain

2. Kingdom

3. Phiylum

4. Class

5. Order

6. Family

7. Genus

8. Species

Discrete Data: A set number; individuals fit into non-overlapping groups (qualitative) or when a variation is a finite number (ex., number of spots, blood group). Continous Data: A range of numbers (any value between a set of numbers); a finite range of overlapping characteristics (qualitative) or values (quantitative) (ex., skin colour, blood group, and height).

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Variation is the difference between characteristics between individuals. In environments, favourable variations cause an increase in population, while unfavourable variations cause a decrease in the population (proposed by Darwin).

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Evolution is the change in inheritable characteristics of a population over time. It helps distinguish Darwinian evolution from Lamarkism. Acquired characteristics that are not genetic in origin aren’t regarded as evolution.

A theory is the way we know something works based on a hypothesis. Facts lead to a hypothesis, which then leads to predictions, and then it becomes a theory that is tested multiple times. Evolution is a fact theory, we know a change has happened but not how.

Lamark & Darwin evolutionary theory:

Natural selection is the process in which populations of living organisms adapt and change to their environment. Natural selection acts as the mechanism during

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evolutionary change. It operates continuously and over a billion years, resulting in biodiversity and life on Earth. It’s a theory that explains the process in which organisms better adapted to their environment tend to survive and produce more offspring. Over generations, natural selection leads to populations adapted for specific environments. In environments, favourable variations cause an increase in population, while unfavourable variations cause a decrease in the population (proposed by Darwin).

Darwin’s theory of natural selection:

● Variations are seen with organisms in a population, heritable and genetic factors are passed onto an offspring.

● Overproduction leads to competition, which leads to struggle for existence. ● “Survival of the Fittest": Applied to organisms with favourable adaptations ● Frequency in favourable traits amongst a population

● Leads to better adaptation

● Isolation in geographical areas prevents inbreeding.

● Environmental differences lead to a favour in certain traits

● Over time, the accumulation of differences can lead to isolated populations as separate species.

● Enables evolutionary change and biodiversity

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Evidence of evolution:

● Fossils

● Slective breeding of domestic plants and animals

● Comparitive anatomy of animals

Genetic variation: differences in genomes among individuals of the same species (if giraffes all had the same length of necks, natural selection wouldn’t be applied). This arises from mutations and sexual reproduction.

Mutations: Errors in replicating DNA while copying genetic information resulting in alleles or the many alternate forms of a gene (allows for new alleles in a population resulting in variation). These are mostly neutral, though some are harmful or beneficial. Only mutations in the cell-producing genes can be inherited. In other parts of the body, there would be no value in introducing variation.

Formulation of gametes involved crossing over and independent assortment of hemologus chromosomes, resulting in unique allele combinations. Random fertilization creates new alleles of both parents. When there are many producing individuals, alleles mix again and again, creating endless variation.

Foods prepared do not meet the demand of a population, resulting in poverty, famine, and wars. Overproduction is frequent when there isn’t enough food to survive according to Darwin.

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All living things need resources (limiting factors as they determine the carrying capacity of the environment).

Selection pressures are factors that lead to different survival/reproduction, causing change in the genetic composition of the population. Includes both density independent and density-dependent factors.

Density dependent: factors effecting size of population, depending on density of the population in a given area focusing on population density.

Density independent: abiotic factors affecting size of population ignoring population density.

Alleles: An alternative form or version of a gene.

Adaptation: The processes in which a species comes fit to its environment.

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In a light forest, it is easier to see dark moths compared to light ones (camoflauging). Light moths have an advantage over dark moths because birds can’t spot them as easily. Because of this, dark moths can’t reproduce. This is an example of a selective advantage for light moths and “survival of the fittest.”.

Before the industrial revolution, the peppered moth had a selective advantage as forests became dark.

Any characteristic or trait that gives an organism a genotype greater chances of surviving and reproducing than the available alternatives. If it continues in the same direction for a large period of time, most of the population will have the beneficial trait (called an adaptation).

Genetic variation:

● Mutations generate new alleles

● Sexual reproduction involved the fusion of gametes

○ Meiosis produces gametes (sex cells) with variation

Carrying capacity is in an ecosystem; there is a limited amount of animals in an ecosystem to be supported long-term in the environment. Carrying capacity individuals compete for resources (food, water, territories, and avoiding predators).

Abiotic factors as selection pressures cause a trait to be more favourable than others in the environment.

Selective advantage: any characteristic or trait that gives an organism or a genotype greater chances of surviving and reproducing than available alternatives.

Sexual selection is natural selection arising through preference by one sex for certain physical or behavioural traits in individuals of the other sex. Sexual selection could be intrasexual or intersexual selection.

Intrasexual selection: Competition for an individual of one sex to mate with the opposite sex. Usually male-male competition for a female, but female-female also is seen. Physical and behavioural characteristics help select mates. For males, it takes forms of size, strength, or elaborate ornamentation.

Intrasexual selection: individuals of one sex (usually female) choosing an inividual of the opposite sex as a mate. This turns strong selection pressures on the characteristic of the opposite sex.

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Evolutionary Fit: To survive and reproduce, sexual selection focuses on reproduction, and for survival it varies (or none at all). Natural selection cares about both.

Pufferish: Predators can easily spot it, mostly to impress the female.

D4.1.7

Differences in physical and behavioural traits, which can be used as signs of overall fitness, can affect success in attracting a mate and so drive the evolution of an animal population.

Colouration of guppies is an inherited trait.

- Predators are more likely to kill them

- Female ones are more likely to mate with colourful ones.

John Endlers Guppies, Lab:

Endler set up fish tanks with guppies and predators present. The bottom of the tanks was covered in either coarse gravel or fine gravel.

What is the appearance of the fish in the initial setup? There is a variation of what the spots look like.

What happens when a predator is present?

The fine and coarse gravel guppies blend in with their environment (coarse gravel has larger dot guppies; fine gravel has smaller spot guppies). The predator was the selective pressure, and the best camouflaged guppies were more likely to survive and reproduce, passing on camouflaged genes to the next generation.

What happens when a predator isn’t present?

Guppies go for the mates that stand out the most, so in coarse gravel guppies with small spots stand out so they’re chosen, in fine gravel guppies with large spots are chosen because they stand out. The visible male guppies are the most visible and are more likely to pass their genes onto the next generation.

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Evidence for evolution includes:

- DNA, RNA, and protein sequences: Known as molecular phylogeny, it determines how closely two species are related to each other at a molecular level (similarity indicates more closely related).

- Homologous structures: Structures look fairly similar (limbs) but carry out different (or same) functions. They indicate divergent evolution, which occurs when organisms arising from the same ancestral species adapt to different environmental conditions according to the pressures of natural selection. Basically, they indicate a common evolutionary organ.

- Pentadactyl limbs are an example of homologous structures that have come from the same ancestors (human, dog, bird, whale).

- Selective breeding: the process of humans choosing plants with desirable traits to breed together and produce offspring with more of those traits.

A4.1.3: Variation between different domesticated animals

Selective breeding of dogs: Humans selectively breed dogs with desirable traits to create the wide variety of dog breeds available today. This is an example of selective breeding.

Changes in the genome (and amino acids specified) are due to mutations. The rate of a mutation is fairly constant and leads to differences in the DNA accumulating over time.

Molecular clock: Measures time from changes in DNA

Example: species with fewer differences in their genomes and amino acids would have recently split or diverged from each other.

Analogous structures: when structures have the same function but dissimilar structure. They’re a result of convergent evolution, which occurs when distantly related group organisms face similar environmental conditions and adapt in similar ways. They are not from the same ancestor.

A4.1.5: Convergent evolution is how analogous structures come to play

Convergent evolution is the evolution of similar structures in species not related due to a recent common ancestor.

Analogous structures: wings

Wings of birds, bats, and insects are analogous structures because wings in all three groups have the same function. None of these groups share a common ancestor of these wings.

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A4.1.6: Speciation is the only way species have appeared (splitting of pre-existing species)

Speciation is the formation of new species through evolution. Occurs as pre-existing species evolve into new species.

Reproductive isolation occurs when there is a barrier that causes two groups to not be able to reproduce with one another. Only occurs when a population is separated. This is often a result of geographic isolation.

Geographical isolation occurs when two populations of the same species are prevented from reproducing because of geographical features such as rivers, mountains, or being on different islands.

Chimpanzees and bonobos were separated as the Congo river became wider, they were relatively isolated and weren’t able to reproduce with one another. The selection pressures were different on both sides of the mirrors.

DNA and RNA:

Sequence data gives powerful evidence of common ancestry.

The biomolecules DNA, RNA, and proteins provide strong evidence of evolution. The same genes are present in organisms that have evolved from a common ancestor. Differences in basic sequences in DNA are a result of mutations.