Chapter 22 Descent with Modification Flashcards
Descent with modification (Darwin’s definition)
Earth’s species today are descendants from ancestral species that were very different from today’s species.
Evolution Overview
A change in the genetic composition of a population from generation to generation.
Pattern and a process,regardless of the definition
Pattern of Evolution - revealed by data from many scientific disciplines; these data are facts about the natural world
Process of Evolution - consists of the mechanisms that produce the observed pattern of change; these mechanisms represent natural causes of evolution
The Darwinian revolution
Challenged traditional views of a YOUNG
Earth inhabited by UNCHANGING species
Classification of species
Who is Carolus Linnaeus?
sought to classify LIFES DIVERSITY “for the greater glory of God”
Developed two-part, binomial format (BINOMIAL NOMENCLATURE) for naming species that is still used today
Linnaeus ascribed RESEMBLANCE among species to the pattern of the creation rather than EVOLUTIONARY kinship.
Fossils
remains or traces of organisms from the past.
Ideas about change overtime
a. Darwin drew on scientist’s work studying FOSSILS
b. Many found in SEDIMENTARY rocks formed from sand and mud that settle to the bottom of seas, lakes, swamps, and other aquatic habitats
c. New LAYERS of sediment cover and compress into superimposed
layers of rock (STRATA)
d. Fossils in a particular strata show which kind of animals existed at the same time.
Paleontology
Study of fossils.
Charles Lyell
principle of unformitariaism (mechanisms of change are constant over time)
same geological forces acting at a constant rate.
Charles Darwin accepted these ideas and they shaped his thinking
The Earth must be much older than people suggest
This same idea could apply to life forms
Lamarck’s Hypothesis of Evolution
Proposed INCORRECT mechanism for how evolution occurred, published in 1809
Two principles used to explain his findings
USE and DISUSE- parts of the body that
are used extensively become LARGER and STRONGER, while those that are not used DETERIORATE
Inheritance of Acquired Characteristics - an organism could pass these modifications off to their offspring (use and disuse characteristics)
Today we know that this is not how traits are inherited.
Jean-Baptiste de Lamarck
visionary recognition that evolutionary change explains PATTERNS in FOSSILS and the MATCH of organisms to their ENVIRONMENTS
Natural Selection
ATTEMPTS to EXPLAIN the ADAPTATIONS of organisms
The Voyage of the Beagle
Primary mission of the voyage was to chart poorly known stretches of South American coastline
While the crew surveyed the coast, Darwin __________ and ___________ thousands of animals and plants and noted ______________ that made them ______-______ to such a diverse environment as the humid jungles of Brazil, grasslands of Argentina, and peaks of the Andes.
1.observed
2. collected
3. characteristics
4. well-suited
Darwin read Lylle’s Principles of __________ while on board
Geology
Thought about geology
When on board, there was an earthquake on the coast of Chile and it thrust rock upward many feet - explained why marine fossils are found at the top of mountains
The physical evidence did not support the fact that Earth was only a few thousand years old
Stop at Galapagos Islands
Hypothesized that the Galapagos had been colonized by organisms that Strayed
from South America and diversifie A
into new species
Adaptations
inherited characteristics of organisms that enhance their survival and reproduction in specific environments
Descent with Modification
Used this phrase instead of evolution
Summarized his view of life he attributed unity of life to the descent of all organisms from an ancestor that lived in the remote past
as descendants of the ancestral organism lived in various habitats overtime that fit them different ways of life descent with modification eventually led to diversity and richness of life
Darwin descent with modification
viewed history of life as a tree with multiple branching from a common trunk out to the tips of the youngest twigs
Tree of descent of modification
tips of twigs represent diversity of organisms, living in present
each fork and branches represent the most recent common ancestor of all the lines of evolution that branch from that point
closely related species share the same line of descent into a recent split from a common ancestor
when an exchange occurs, there are no living species to fill that gap in the tree (fossil show us where these gaps are)
this messed well with the Linnaean model of classifying life
Artificial Selection
process by which humans modified
other species over generations by selecting and breeding generations that possess desired traits (Darwin)
Natural Selection
is a similar process that occurs in nature
Based this idea on 2 observations and inferences
Observation #1
members of a population vary in their inherited traits
Observation #2
all species can produce more offspring than their environment can support and many of these offspring failed to survive (die)
Inference #1
individuals who inherited traits give them a higher probability of surviving and reproducing in a given environment tend to have more successful offspring than other individuals
Inference #2
unequal ability of individuals to survive and reproduce will lead to accumulation of favorable traits in the population over generations
What can influence an organism’s performance and its offspring’s ability to cope with environmental changes?
An organism’s heritable traits.
How does a parent’s advantageous trait affect its offspring?
If a parent has a trait that helps it escape predators, obtain food, or tolerate the environment, its offspring will likely inherit this trait, increasing their chances of survival.
How quickly can artificial selection occur compared to natural selection?
Artificial selection can occur very quickly, while natural selection happens over several generations.
What happens to advantageous heritable traits over time?
Advantageous variations accumulate in the population, while less favorable variations diminish.
What is one of the main ideas of the Theory of Natural Selection?
Individuals with certain heritable traits survive and reproduce at a higher rate than others due to those traits.
What effect does natural selection have on the match between organisms and their environment over time?
Natural selection can increase the match between organisms and their environment over time.
What is the outcome if an environment changes?
The text suggests that natural selection will refine the match between organisms and their environment over time, implying organisms may need to adapt if the environment changes.
What causes populations to evolve?
Natural selection, not individuals, causes populations to evolve.
Can natural selection act on identical genetic traits?
No, natural selection can only amplify or diminish heritable traits that differ in a population.
Does natural selection occur if all individuals are genetically identical?
No, natural selection cannot occur if all individuals in a population are genetically identical.
How do environmental factors affect evolution?
Environmental factors vary from place to place and over time, affecting the favorability of traits.
What are the four types of data that support evolution?
- Direct observation of evolutionary change
- Homology
- Fossil record
- Biogeography (Note: Only two are mentioned in the text)
Give an example of direct observation of evolutionary change.
Natural selection in response to introduced plant species, such as beak lengths evolving to match food sources.
How do bacteria develop drug resistance?
Bacteria can destroy certain antibiotics or change their cell wall composition to resist the antibiotic.
Define homology.
Similarity resulting from common ancestry.
What is a common feature of related species that may have different functions?
Related species can have characteristics with underlying similarity but function differently.
Give an example of anatomical homology in mammals.
The forelimbs of all mammals show the same arrangement of bones from the shoulder to the tops of the digits, despite having different functions.
What are vestigial structures?
Vestigial structures are remnants of features that served a function in the organisms’ ancestors.
Name an example of a vestigial structure in snakes.
The skeleton of snakes still has some remnants of pelvis and leg bones from their walking ancestors.
What is significant about the genetic code at the molecular level?
All organisms use the same genetic language of DNA and RNA, and this genetic code is essentially universal.
What is an evolutionary tree?
An evolutionary tree is a diagram that reflects evolutionary relationships among groups of organisms.
What can the early stages of development in different animals reveal?
They can reveal additional anatomical homologies not visible in adults, like tails and pharyngeal pouches.
What is the function of pharyngeal pouches in different species?
They develop into gills in fishes and parts of the throat and ears in mammals.
What does each branch point on a phylogenetic tree represent?
Each branch point represents the common ancestor of all species that descended from it.
How are homologies depicted in a phylogenetic tree?
Homologies are shown in a nested pattern, where a homology present in an ancestor is present in all its descendant species.
How can you determine how closely related two organisms are on a phylogenetic tree?
By looking at the most recent common ancestor they share.
What do the relative positions of branch points on a phylogenetic tree indicate?
They show the relative times of evolutionary events, indicating which ancestors existed before others without exact dates.
Cladogram
how organisms are closely related in terms of evolution
What is the basis for confidence in relationships expressed in evolutionary trees?
Confidence is based on the strength of supporting data, such as anatomical and DNA sequencing data sets.
What is convergent evolution?
It’s a phenomenon where organisms resemble each other not because of common ancestry, but because they have independently adapted to similar environments in similar ways.
What is the difference between analogous and homologous features?
Analogous features arise from convergent evolution and do not indicate common ancestry, while homologous features do indicate common ancestry.
How does the fossil record contribute to our understanding of evolution?
It documents the pattern of evolution, showing differences from past organisms to present-day organisms, and indicates that many species have become extinct.
What role does biogeography play in evolution?
It examines the distribution of species and is influenced by factors like continental drift.
What does “endemic” mean in terms of species distribution?
Endemic species are native and often found nowhere else in the world.
