Date: _________

Agenda

Warm-Up- Review Natural Selection and Reproduction for quiz today!!!!

Notes on Evidence of Evolution

Work on Vocabulary and Lab

Ask questions based on 5.1 and 5.2

Quiz on 5.1 and 5.2

How do we know? The fields of anatomy, embryology, biochemistry, and paleontology have contributed the scientific evidence for the theory of evolution.

Scientists study data to trace the phylogeny (evolutionary history) of a species or a group of related species.

Based on this data, the theory of evolution states that all forms of life on Earth are related because the ancestry of organisms can be traced back to a common origin.

Anatomy Study of the structures of organisms

Involves convergent and divergent evolution

Convergence: completely different organisms adapt to similar environments and develop analogous (similar) structures

Divergence: a single species or two similar species evolve different structures over time

Evidence has been from

Homologous structures

Geographical locations

Anatomy...Homologous Structures Homologous structures: similar characteristics resulting from common ancestry

The more homologous structures two organisms share, the more closely they are related

Vestigial organs: structures with little or no function to the organism

Important in the ancestors of that organism

Homologous Structures

Anatomy...Geographical Location If the location is different but the environment is similar, species can develop similar structures and behaviors

If a species encountered a different ecosystem because of a change in geographical location, new anatomical traits come about

A new species evolves with a shared common ancestor from the original population

Embryology Embryology: the study of the embryonic development of organisms

Similarities in development is

more similar during embryonic

development versus in adults

Vertebrate embryos look very

similar, but vary greatly as they age and develop These similar structures may suggest that these species evolved from common ancestors

Evolution may have selected for new stages at the end of embryonic development

Growth and development mimics phylogeny – how we are related

Biochemistry Biochemistry: study of the chemical processes in organisms

Genes and proteins support biological evolution

The more similar DNA and amino acid sequences in proteins of two species are, the more likely they have a common ancestor

Evolutionary relationships can be traced through DNA when anatomical structures are not helpful

Species may be so closely related that they don’t appear to be different

Species may be so diverse that they share few similar structures

Biochemistry Changes in DNA and proteins increase over time

The greater the genetic similarity, the more recent the common ancestor is

The time since a pair of species have diverged can be estimated under a “molecular clock”

DNA sequence comparison may be the most reliable evidence, but there are challenges

Genes evolve at different rates and it can be difficult to pinpoint divergence

DNA changes (like mutations) can cause problems in aligning and comparing chromosomes

Assumptions and human error may result

in different phylogenetic trees

Natural selection can cause convergence in molecules

Paleontology Paleontology: study of prehistoric life

The fossil record provides evidence of life forms and environments along a timeline and supports evolutionary relationships by showing the

similarities between current species and ancient species Comparing current and ancient species shows gradual change

Fossil record tells a story of the types of organisms that have lived on Earth (including those that are extinct) and the relative ages of the fossils

Fossil record is incomplete – most organisms do not form fossils! Many gaps are filled as more fossils are discovered.

The older the fossils, the less they look like modern species

Paleontology Fossil record shows divergence in phylogeny

Transitional fossils show links in traits between groups of organisms – these confirm evolutionary relationships

However, fossil record is incomplete Fossils are VERY RARE and hard to form

Fossil record favors species that existed for a long time, abundant and widespread, and had hard shells or skeletons

Gaps in the fossil record do not indicate that it is WEAK as far as evidence is concerned, but rather points out additional research opportunities – gap filling fossils are CONTINUALLY discovered

Just keep in mind... One piece of evidence does not ensure an accurate picture of the history of evolution in a particular group of organisms

Scientists collect many pieces of evidence from many fields

The more evidence from different fields, the more reliable the information is

Evolutionary theory is a well-tested explanation that accounts for a wide range of observations made by scientists in many fields of science

Evolution is not completely understood – many unanswered questions remain to be studied and analyzed

Finish vocabulary and yesterday’s lab.

Review for 5.1 and 5.2 Quiz (Study Guide)

Notebooks are DUE TOMORROW!!!!

Vocabulary

Cartoon sequence questions

Peppered moth lab