Darwin's Model of Natural Selection:
- Populations are made up of individual
organisms whose traits (structural, behavioral, biochemical) exhibit
variation from one individual to the next.
- Many trait variations are inherited.
- Some trait variations may be advantageous
while others may not be.
- Whether or not a variation is advantageous
depends on the environment within which a population lives.
- The frequency of particular trait variations
in a population may change over time due to differential survival and
- Evolutionary changes occur in populations
or species, not individuals.
- Offspring are not exactly like their
parents-they also vary, but the variations of their traits are likely
to be similar to those of their
- Variability in a population can be represented
- Organisms produce more offspring than
- There is competition between organisms
Models of Paley and Lamarck:
- Paley's model invokes an intelligent designer
to account for the apparent perfection of organisms' adaptations to
- Paley believed species to be fixed and
unchanging, each having an "essential" type that set it apart
from all others.
- Lamarck's model invokes the needs of organisms
to account for species change.
- Lamarck believed that inheritance could
be affected by the use or disuse of particular body parts.
Throughout the Natural Selection unit, students
will learn about the practice of science-building, critiquing, and using
models that account for particular phenomena. Our intention is that students
will learn about this process and also be able to engage in it. Thus,
the nature of science learning outcomes include skills necessary for the
practice of science (modeling) as well as concepts about such practice.
Learning outcomes related to scientific arguments:
- Several inferences make up most scientific
- Inferences are based on data (observations)
and prior knowledge and beliefs.
- It is possible to critique arguments based
on observations or the prior knowledge and beliefs used.
Learning outcomes related to modeling:
- Models are judged to be acceptable or
not based on how well they explain the data, how consistent they are
with other knowledge, and how well they can be used to predict new data.
- Models are ideas that scientists use to
explain patterns they see in the world.
- A model is an idea that has predictive
and explanatory power and is consistent with other ideas about how the
- Models can be compared based on data,
the inferences made in the model, and the prior knowledge and beliefs
upon which they are based.
Learning Outcomes related to historical reconstruction:
- Not all scientific practice is based on
- Evolutionary biology has as a central
goal reconstructing past events.
- Historical reconstruction involves making
inferences about past events based on data available today.
- recognize data patterns
- create models to account for phenomena
- identify components of model
- design experiments to test models
- assess models for data fit and consistency
- revise models based on additional data
(model extension) / effect to cause reasoning
- use model to make prediction
- use of classroom norms (basic interpersonal
- make observations
- organize data
- make diagrams
- create graphs
- analyze graphical data
- use props or other representations to
create or communicate explanations