BIO EPORTINGS TOPICS

Geographical Isolation

is a term used to describe the Physical separation of populations of organisms from one another due to geographical barriers. This type of isolation can lead to the development of distinct and physical characteristics in different populations, and the evolution of new species

Ecological isolation

is a pre-zygotic reproductive barrier where two species or populations live in the same general geographic area but occupy differenthabitats, breeding seasons, and feeding preferences causing them to rarely encounter each other and interbreed

Habitat isolation

This is a specific form of ecological isolation that focuses strictly on physical location or microhabitat where the organisms live ( trees vs pond)

Behavioral isolation

is a prezygotic reproductive barrier where differences in mating behaviors like courtship rituals or mating calls prevent two populations or species from breeding even when they live in the same place

Behavioral isolation

is a way two species stay separate without any physical wall between them. The barrier is behavior. If one species of firefly flashes in a specific pattern and another flashes differently, they will not mate since individuals only respond to their own kind. No matching signals, no mating

Reproductive Isolation

is a collection of mechanism, behaviors and physiological processes that prevent the members of two different species that cross or mate from producing offspring, or which ensure that any offspring that may be produce is not fertile

Mechanical Isolation

is a type of reproductive barrier that keeps two species from interbreeding because their reproductive parts simply dont fit together. In animals, this often means genitalia are shaped so differently that mating physically cant occur. Inplants, it can mean a flower’s structure only matches the bdy of a specific pollinator, so pollen from one species never reaches another.

Lock-and-key idea

body parts or flower structures are shaped so only the same species can successfully mate or pollinate

Prezygotic

it works before a zygote forms, so no hybrid embryo is ever made

Animal example

this often means genitalia are shaped so differently that mating physically cant occur

Gametic isolation

is a prezygotic reproductive barrier where gametes from different species come into contact but fail to fuse and form a zygote.

Gametic Isolation

is the molecular checkpoint at the moment gametes meet, and it helps maintain species boundaries by making sure fertilization only happens within the right species.

how gametic isolation works

Species Recognition:

Matching gametes allow fertilization, while mismatched gametes prevent it. Molecular Mismatch:

Sperm and egg have specific proteins and receptors that must match. Species Boundaries:

It prevents hybridization even when different species reproduce in the same place and time.

Chemical Attractants

Chemical signals help attract and activate sperm from the correct species.

Surface Proteins and Receptors

Matching proteins allow sperm and egg to bind; mismatched proteins prevent fusion.

Post-zygotic isolating mechanism

are biological blocks that happen after fertilization to stop two different species from producing healthy, fertile offspring

Hybrid inviability

is a post-zygotic reproductive barrier where a hybrid embryo is created but cannot develop normally or survive to species from successfully interbreeding and producing lasting lineages, even if mating and fertilization successfully occur

Hybrid sterility

a form of post-zygotic reproductive isolation in which two different species produce a living hybrid, but the hybrid is unable to produce fertile offspring. It occurs after fertilization and prevents the hybrid from successfully reproducing. (OpenStax Biology 2e, 2018)

Hybrid Sterility

Two different species mate + produce an offspring =

offspring has difficulty in surviving and producing.

Hybrid Breakdown

is an isolating mechanism that occurs when two different species produc healthy and fertile 1st generation hybrid, but the 2nd generation hybrid have complications. Such complications include low survival, reduced fertility and death

Speciation

it is the development of new, unique species during evolution. A single evolutionary lineage can split into two or more genetically process distinct lineages,known as speciation

Allopatric Speciation

occurs when a species gets split into two geographically isolated populations. This is oftenthe result of geological events such as mountain building. The isolated populations may then be subjected to slightly different conditions and therefore selection occurs

dispersal,vicariance

Types of allopatric speciation

dispersal

movement of individuals and species, which is a crucial process infuencing global biodiversity patterns and is particularly evident in overwater dispersal events among species on oceanic islandsj

Vicariance (allopatric speciation)

a process of geographic isolation that occurs when a physical barrier, such as the opening of an ocean, separates populations, leading to divergence in species

peripatric speciation

one group is smaller than the other, unique characteristics of the smaller groups are passed to future generations of the group making those traits more common among that group and distinguishingit from the others

Sympatric speciation

occurs when a single ancestral species diverges into distinct groups while occupying the same geographical region, eventually developing reproductive barriers that prevent interbreeding

Parapatric speciation

is a type of speciation in which two populations live in neiboring or adjacent areas but experience different environmental conditions. They may still have some gene flow but differences in their environment can cause them to evolve differently

Mutations

are a key driver of evolution because they
create genetic variation within populations, allowing
organisms to adapt and evolve over time
(Loewe et al., 2010).

Internal Factors

Mutations happens when DNA is copied incorrectly
or spontaneously breaks down, despite the cell’s
mechanisms for detecting and repairing these errors
(Wu,2020).

External Factors

Mutations can also be caused by external factors,
such as exposure to certain chemicals, radiation, or
other environmental agents that can damage DNA
(Wu,2020).

Somatic mutation

change in the DNA of
body cells that occurs
after conception and is
generally not passed on
to the next generation

somatic mutation

change in the DNA of
body cells that occurs
after conception and is
generally not passed on
to the next generation

Somatic mutation

are changes in the DNA of body cells that may result from replication
errors or exposure to external factors. These mutations are generally not inherited and
may contribute to conditions such as tumors and other health problems (Oota, 2020).

Somatic mutation

Spontaneous copying errors during cell replication, radiation, toxic chemical
exposure, and oxidative stress.

Cancer

the most common somatic mutation

Sickle cell disease

is a mutation in the sex cells or gamates (the sperm cell in males and
the egg cells in females), can be hereditary and can affect future generation.

Natural selection

is the process which also known as survival of the fittest, the process whereby organisms better adapted to their environment tend to survive and produce more offspring. The theory of its action was first fully expounded by Charles Darwin and is now believed to be the main process that brings about evolution.

Artificial selection

is the process in which humans intentionally choose organisms with desirable traits and allow them to reproduce so that those traits can become more common in future generatiins. it is called selective breeding. Unlike natural selection, where environmental conditions influence which traitsa are favored, artificial selection is directed by humans

Gene Flow

also called gene migration or allele flow, happens when individuals move to another population and reproduce

Genetic Drift

is the random change in the frequency of alleles in a population due to change, it happens because not all individuals reproduce or pass their alleles to the next generation equally, and these differences can occur randomly

Genetic drift

it is stronger in small populations where random events can have a greater effect on which alleles are passed on. As a result, some allels may become more common, less common or disappear over generations

Bottleneck effect,founder effect

causes of genetic drift

bottleneck effect

this occurs when a populations size is suddenly and greatly reduced due to catastrophic or disturbance

founder effect

this occurs when a small group of individuals separates from a larger population and establishes a new population