Biology 221 lecture Unit 1

step 1 Observation

Scientific method: the act of describing things you see in for ex different pictrues

step 2. formulating a question

Scientific method: the act of creating a question based on the observations. How or why something happens

step 3 Hypothesis

Scientific method: the act of creating a guess for the possibility of something happening to answer the question

step 4 Prediction

Scientific method: the act of guessing whats going to happen if the hypthesis is correct.

Step 5 Expirament

Scientific method: the process of testing the hypothesis through controlled procedures to gather data and observe outcomes.

step 6. Analyzing data and drawing a conclusion

Scientific method: the process of evaluating collected data to determine whether it supports the hypothesis, leading to a final conclusion.

Example of step 1: observation

all zebras have stripes

Example of step 3: hypothesis

the possible reason for why zebras have stripes by be to better regulate internal temperature

Example of step 2: question

why do zebras have stripes?

Example of step 4; prediction

striped zebras will have a cooler boy temperature than other animals who don’t have stripes in the same habitat.

the graphing and showing of the results of temperature measurements and analyzing the data to support or refute the hypothesis.

Step 5. expirement

example of step 6; analyzing and drawing conclusion

the graphs do not support our hypothesis, zebras actually retain more heat then non-striped animals

why do zebras actually have stripes according to the expiraments?

to avoid biting flies

what is evolution?

1. a change in characteristics that are able to be passed down to offspring

2. it can only happen in populations

3. its change in genes; alleles, genotype (set of genes carried by an organism) and phenotype (observable traits)

natural selection

the process in which organisms with traits suited for their environment tend to have a higher change at survival and reproduce, passing those traits to the next generation.

Genetic Drift

the random change in allele frequencies in a population due to chance events, leading to evolutionary changes over time.

Mutation

a change in the DNA sequence of an organism's genome, which can lead to new traits and contribute to genetic variation within a population.

Gene flow

the movement of genes/traits through an organism, often through migration, which can increase genetic variation and influence evolutionary processes in the new population.

Illustrate Directional selection

A form of natural selection that favors one extreme phenotype over others, causing the allele frequency to shift in a consistent direction, which can lead to adaptation in a specific environment.

illustrate stabilizing selection

a form of natural selection that favors traits in the middle not choosing either end, it decreases variation and stabilizes a population.

disruptive selection illustration

a form of natural selection that

1. increases genetic variation

2. favors both extreme phenotypes over phenotypes in the middle

3. and can split the population into two pop.

effects of directional selection

1. increases fitness

2. decreases variation

3. and favors one side shifting the mean value to one extreme end

effects of stabilizing selection

1. doesn’t shift mean value because it doesn’t favor either extreme

2. makes the bell curve slimer and taller

3. decreases variation

effects of Disruptive selection

1. increases genetic variation by favoring extreme phenotypes

2. can lead to the splitting of a population into two distinct groups

3. results in a bimodal distribution of traits. creating tow peaks on the ends of the bell curve

Examples of directional selection

giraffes have longer necks due to the type of food they consume. So long necks are favored.

example of stabilizing selection

preference for average body size in certain species, where both very small and very large individuals are less likely to survive and reproduce. This selection maintains the population's average traits.

example of disruptive selection

when a population of birds has a variation of beak sizes and the environment provides a variety of sized nuts. The population will favor both small and large beak sizes, leading to two distinct groups that are well adapted to their specific food sources.

Causes and Concequences of Genetic drift

1. when random effects like natural disasters occur

2. it decreases genetic variation because it can lead to the loss of alleles in small populations, changing allele frequencies and affecting population dynamics.

when does gene flow occur

1. when an organism from one population moves to another

2. increases genetic variation in the process because the organism introduces a new gene.

effect of natural selection

1. decreases genetic variaton bec it focuses on survivable traits for the habitat

2. increases fitness because the organism has the best trait for the environment

3. organisms often survive and have offspring

effects of mutation

1. increase in genetic variation because it introduces a new gene on an organism

2. It can be beneficial, harmful, or neutral, on average fitness

effects of genetic drift

1. Decreases variation, epsecially in small populations.

2. It can lead to reduced fitness due to the loss of beneficial alleles.

Effects of gene flow

1. Increases genetic variation by introducing alleles from one population to another.

2. It can enhance or reduce fitness depending on the compatibility of the introduced genes with the local environment.

Interpretation of Graphs: shifts completely to one end

directional

Interpretation of Graphs: becomes slim and tall.

stabilizing

Interpretation of Graphs: splits into two seperate peaks

Disruptive

Interpretation of Graphs: changes the ration of genetic variation

natural disaster occurence (gentic drift)

Interpretation of Graphs: a small part of the population migrates

Gene flow

evolution by natural selection

the process where organisms with helpful traits survive and have more babies, evolution by passing those traits to the next generation

Fitness:

the ability of an organism to survive, reproduce, and pass on its genes to the next generation. It is a measure of reproductive success.

Adaptation

an heritable trait that increases the organisms possibility of survival and reproduction

the four criteria needed for evolution by natural selection:

1. variation in traits among individuals

2. the heritability of traits

3. differential survival and reproduction of individuals

4. the presence of a selective pressure that influences survival and reproduction

Description of anoles: trunk-crown

1. short legs, big toe pads, and green

2. they live on the upper part trees and on leafs.

3. Large toe pads provide support and grip on leaves and the smooth part of the trees.

Description of anoles: trunk-ground

1.  long legs, big bodies and usually brown.

2. they inhabit the lower parts of trees and the ground.

3. smaller toe pads help them navigate rough bark and ground surfaces.

Description of anoles: Twig

1. short legs, slender bodies, and short tails in order to blend into the twigs and branches they live in

2. They have slender bodies and tails to help provide support when crossing twigs etc.

3. usually exhibit coloration for camouflage.

Description of anoles: grass-bush

1. small bodies, slender limbs, often green or brownish in coloration.

2. They inhabit grassy areas and low shrubs, adapting to blend in with their surroundings.

3. long tails help them tavel along grass w/o falling over

which critera is applied to anole habitat: they each have a certain part of their body that helps them move across their habitat. They were caused by genetic mutations that helped them survive. Ex: long legs, large toe pads.

variation in phyisical traits

which crieteria is applied to anole habitat:

due to the variation and when the people in the video went back again, they were most likely passed down from parent to offspring. 

Heritability

which criteria is applied to anole habitat:

different types of anoles were able to reproduce and pass down the different genes for survival, although some survived and some didn’t.

fitness influence

which criteria is applied:

those that had mutations to adapt to their part of the habitat, the other lizards when going to those habitats, were easily overpowered.

Adaptation

Define species

A group of organisms that share similiar characteristics but can breed with one another and produce fertile offspring

define speciation

The evolutionary process through which new biological species arise.

involving genetic divergence and reproductive isolation from the ancestral species.

genetic divergence

populations begin to evolve independently of each other

genetic isolation

elimination of gene flow between populations

what is the species concept that defines the species by its potential of interbreeding and fertile offspring production

biologcial species concept

what is the species concept that defines a species by its body shape, size, and features

morphological species concept

what is the species concept that defines a species as the smallest group of organisms sharing a common ancestor:

phyolognetic species concept

synomorphy; a trait found in two or more taxa present

what are Prezygotic barriers

reproductive mechanisms that prevent mating or fertilization between species. These barriers include temporal, habitat, behavioral, mechanical, and gametic isolation.

what is the prezygotic barrier with the description: species inhabit different habitats around the same area but don’t meet often

habitat isolation

what is the prezygotic barrier with the description: when species breed at different times of day, season, or years

temporal isolation

what is the prezygotic barrier with the description: unique courtship rituals or behaviors (a bird song) by individuals that prevent mate recognition

behavioral isolation

what is the prezygotic barrier with the description: when the parts are unable to come togethere or are anatomically different that prevent succesful mating

mechanical isolation

what is the prezygotic barrier with the description: when the gametes are not compatible

Gametic isolation

postzygotic description

refers to mechanisms that occur after fertilization, inhibiting the development or viability of hybrid offspring.

what is the postzygotic barrier with the description: when two species are not gnetically compatible so the embryo doesn’t develop properly causing it to be weak or die

Hybrid inviability

postzygotic barrier with description: when the offspirng survives but cannot reproduce

Hybrid sterility

the biological species concept

based on reproductive isolation and genetic similarity in sexually reproducing organisms.

morphological species concept

classification based on physical characteristics and traits to distinguish species.

Species concepts: phyologenetic

classification based on evolutionary history and relationships among species, often using genetic data to define species boundaries.

ecological species concepts

classification based on the ecological niche and habitat preferences of organisms, focusing on their role in the ecosystem.

example 1: two frogs live in the same habitat but one type breeds during the spring and other during fall

temporal isolation

ex 2: when two birds attepmt to mate but their reproductive organs dont fit together

mechanical isolation

ex 3: a donkey and a horse reprodcue but the offspring (mule) is not fertile

hybrid sterility

advantage and disatvantage: biological concept

1. a: reproduction isolation, connects to gene flow.

2. d: But can’t be applied to asexual organisms, and is difficult to identify.

advantage and disatvantage: morphological

1. a: easy to apply to everything.

2. d: relies on what you can see.

advantage and disatvantage:phylogenetic

1. a: it allows scientists to predict biological traits and evolutionary relationships more accurately by mapping them onto an evolutionary tree

2. d: relies on being able to extract the DNA and test it.

3. d: Genetic background, hard to extract.

Why is distinguishing species important:

1. Conservation; helps protect the animals who are at possibility of extinction

2. It helps track diseases, and everything along those lines.

3. Helps understand ecological roles, evolutionary history, and ecosystem stabilizing.

how can speciation occur? 1. a physical barrier tha divides a population into isolated groups that prevents gene flow. it has two types

Allopatric speciation

1. Dispersal: involves organisms moving to new areas and establishing separate populations.

2. Vicarience: involves the division of a species' range by a physical barrier, leading to isolation.

how can speciation occur? 2. sympatric speciation

Occurs without physical barriers, often through behavioral or ecological differences. It can result from polyploidy or habitat differentiation within the same geographic area.

Ex 1: a rising mountain splits a population isolating groups on opposite sides

allopatric speciation > vicarience

Ex 2; a new mutation occurs that makes an organism reproduce with itself only, isolating it from the original population

sympatric speciation > polyploidy

what is polyploidy?

The condition in which an organism has more than two complete sets of chromosomes, often resulting from a failure in cell division. it can lead to speciation, particularly in plants.

what is the purpose of a fossile record?

1. To provide evidence of the history of life on Earth

2. Documenting the evolution of species over time

3. Offering insights into past environments and organisms.

Explain the limitations of the fossile record

1. its incomplete

2. often biased towards hard-bodied organisms, and may not represent all species or time periods.

3. Fossilization is a rare event, making it difficult to fully capture the diversity of past life.

fossile record bias: organisms with hard parts are more likely and easily fossilizes compared to mostly soft part organisms

Anatomical Bias

fossile record bias: organisms in certain areas that sediment gather more often than not, are more likely to be preserved over other organisms in different habitats

Evironmental Bias

fossile record bias: Many of the extremely old fossils could have been destroyed by the many events over the years, shifting of tectonic plates, and destruction of the place in general. while the newer fossils haven’t been affected as much because they where fossilized not long ago.

Temporal Bias

fossile record bias: Species with a great amount of organisms are more likely to be fossilized than the rare species, because of the amount there are in each species.

abundance bias

Adaptive radiation

The process in which a single ancestral species rapidly evolves into diverse forms to adapt to different environments, leading to increased biodiversity.

Mass extinction

a widespread and rapid decrease in the biodiversity on Earth, typically characterized by the loss of a large number of species in a relatively short geological time frame. (less then 1 million years)

What triggers adaptive rationation?

1. environmental changes

2. availability of new resources

3. the emergence of new niches allowing a species to diversify and exploit various habitats.

4. a main predator dies out

Background extinction

The normal rate of species extinction that occurs over long periods due to natural processes.

Mass extinction

Occurs when a significant number of species die off in a relatively short geological period, and are rare events that significantly alter Earth's biodiversity Ex: asteroind/comet impact

Explain the hypothesized mechanism(s) of specific adaptive radiations

occurs through mechanisms such as ecological opportunity, where the availability of new resources or niches drives diversification, and morphological innovation, where changes in physical traits enable species to exploit different environments.