Ecology and Evolution (Lectures 1-3)

the beginning of the end

What is science?

• A way of knowing

• Generates reliable knowledge about measurable things, enabling us to make predictions

What is science good at?

• it is falsifiable, repeatable and offers a way to see past anecdotes and stories (ex. religion)

• Can be adjusted as new evidence is made available.

What makes great discoveries?

• Keen observations

• Seeing what has previously been missed

What is ecology?

• Study of natural communities

Who is Charles Darwin?

• English naturalist known for developing the theory of evolution by natural selection.

• Studied beaks of Galapagos finches.

Who is Alfred Wallace?

English naturalist who proposed the theory of evolution by natural selection, contributing significantly to the field of biogeography. Co-published with Darwin.

What did humans know about traits and selective breeding?

• certain traits could be passed from parents to offspring

• Animals and plants were selectively bred for desirable characteristics - traits could be manipulated in some way.

What is biogeography?

• Patterns in distribution of organisms and communities

What is the wallace line?

A fauna boundary that separates the ecozones of Asia and Australia, reflecting distinct communities and species distribution

Why were the tortoises’ shells different in different islands of the Galapagos?

• They adapted to different environmental conditions, such as vegetation type and availability, which influenced their feeding habits and appearance.

Who noticed the variance in Galapagos tortoise shells?

Charles Darwin, during his voyage on the HMS Beagle.

What is the transmutation of species?

• Species can change over time through evolutionary processes, leading to the emergence of new species from common ancestors.

How does the transmutation of species happen? (4 mechanisms

• genetic variation

• natural selection

• environmental factors

• speciation events

Who came across the Galapagos finches?

Charles Darwin

What is a selective event?

• Where certain individuals with specific genes are more likely to survive, or “be selected”

What is evolution by natural selection?

• Organisms better adapted to their environment are more likely to survive. Overtime, these traits will become favorable as those who fail to adapt die off.

What is an example of natural selection?

Galapagos finches adapted to new food sources, developing beaks of different sizes. Those with larger beaks survived as those who failed to adapt, starved.

Does the environment have a direct impact on the evolution of species?

Yes, the environment influences which traits are favoured, and species will evolve towards these favourable traits.

Explain ecological complexity.

The study of the complex interactions between living systems and their environment, and the resulting consequences from these interactions

Did all life evolve from one single ancestor?

Yes, the Last Universal Common Ancestor (LUCA) was a single celled bacterial organism from which all life originated from (3.5-4.2 billion years ago)

Is evolution still occurring?

• Yes, evolution is a slow process that is constantly happening.

How many species of weevils are there?

More than 80 000.

What larger group are weevils a part of?

Coleoperta

What percent of insects is made up of beetles?

Around 40%

Why are there so many species of weevils?

• Close association with lineage of flowering plants that diversified drastically

• They have a narrow niche that nothing else can fill

• Lots of isolated habitats

• Short generation time

What percent of eukaryotes is made up of beetles?

25% of all species

What percent of species are insects?

Half (50%)

How many species of insects are there?

Millions

How many eukaryotic species are there?

~8.7 million

What does evolutionary/phylogenetic biodiversity vary through?

Time and space

How did biodiversity arise?

Evolution!

What is evolution?

Changes in allele frequency across generations

What are the two basic ways to study evolution?

Mendelian and quantitative

When do you get mendelian variation?

Through genetic variation - not all individuals have the same alleles

What is allele frequency?

How often an allele appears in a gene pool

What are the three genotypes

Homozygous dominant (AA) homozygous recessive (aa) and heterozygous (Aa)

What are genetic changes in quantitative traits controlled and influenced by?

• Changes in allele frequency at multiple genes

• Heavily influenced by the environment

What are the key mechanisms of evolution? Can they influence one another?

• Mutations

• Genetic drift

• Gene flow

• Natural selection

• Sexual selection

YES, they can influence one another.

What are mutations?

Changes in genetic code, generating new alleles. This can change amino acid sequences.

Do most mutations increase or decrease fitness?

Decrease by about 2%

What are mutations that decrease fitness called?

Deleterious

What are beneficial mutations called?

Hopeful monsters

What is genetic drift?

A random change in the allele frequency of a population (ex. natural disaster kills a lot of the population).

Is genetic drift more favourable in small or large populations and why?

Small populations as large populations are less affected by random changes in allele frequency.

Why do most populations remain relatively stable in the number of individuals even though all organisms have the potential for exponential growth? What does this imply?

Limiting factors (ex. carrying capacity) implies a high mortality in nature.

What are the three characteristics of traits?

traits…

• Vary among individuals

• Are heritable

• Influence survival

What did Charles Darwin do to showcase the power of selection?

Used domesticated finches and analyzed the size of their beaks following a drought; only those with larger beaks were able to find food, thus more of them survived.

What is sexual selection?

Members of one biological sex show preference towards specific traits in the other sex; these preferred traits are then more prominent in following generations.

What is speciation?

The evolutionary process resulting in the formation of a new species.

What is the difference between inter/intra-sexual selection?

• Intersexual: choice of females

• Intrasexual: competition between males

What is gene flow?

The movement of genes among populations, often opposing effects of diverging natural selection

What does it take to get speciation? (3 things)

• Reduced gene flow

• Different evolution between lineages

• Reproductive isolation

Give examples of reduced gene flow

• Geographical separation (different islands)

• Local physical separaiton (ground vs in trees)

• Temporal separation (early vs late blooming in season)

Give examples of evolution between different lineages.

• VIA different selection (eg. selection of red flowers in one population, yellow in another)

• VIA drift (differentiation by chance)

List possible reasons for a species being so abundant.

• increased likelihood of reduced gene flow

• increased likelihood of differing selection

• increased likelihood of reproductive isolation

How does the environment influence selection & speciation?

• Dispersal barriers

• Depends on what niches are available

• Abiotic factors (climate)

• Biotic factors (pollinators)

What are the three possible responses to change?

• Move

• Adapt

• Die out

How can species adapt to a new environment?

through phenotypic plasticity

What is phenotypic plasticity? (With example)

When you get different phenotypes from the same genotype (ex. same species of birds migrating at different times, adapting to the weather changing at different times of year).