Species Distributions - Danielle Clements
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School
University of Maryland, Baltimore County *
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Course
142
Subject
Geography
Date
Dec 6, 2023
Type
Pages
4
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Factors affecting population and geographic distribution of a Species
Turn in your completed graphs with your document on
Blackboard by the end of your section! You should have at
least 2 graphs (questions 4a and 4e) with the appropriate
labeling.
Questions in blue are recommended to be completed/attempted on notebook paper BEFORE you meet in
active learning. Also make sure you read the "Crabs of Christmas" on blackboard before active learning.
https://www.damninteresting.com/the-crabs-of-christmas/
The distribution of most species is confined to specific geographical areas. Understanding the causes and
consequences of this is a key goal of ecology, biogeography, and evolutionary ecology. A number of factors
(both biotic and abiotic) play a role in determining the geographical distribution of species. In this module we
will explore these factors and the relationships between them. We will also explore how these factors influence
the geographical distribution of species and learn ways to express and interpret these relationships
quantitatively.
1
.
List 3 biotic and 3 abiotic factors that might influence the geographic range of a species.
The Christmas Island red crab,
Gecarcoidea natalis
, is a species of terrestrial crab endemic to Christmas Island
in the Indian Ocean. Given below are population sizes (the Y axes) of different organisms on Christmas Island
over the years (1800-2010).
2.
Based on the data, what could be one possible ecological relationship between the red crab and Maclear’s rat
that would explain the patterns in population size over time? Support your answer with references to the data.
3
.
Based on the data, what could be one possible ecological relationship between the yellow crazy ant and the
red crab that would explain the patterns in population size over time? Support your answer with references to
the data.
Open the Excel spreadsheet from Blackboard entitled "species distribution and density data".
In the leftmost
column is the latitude (distance from the equator) and in each remaining column you will find the population
sizes of subpopulations of Species A-F.
Answer the following questions with your group.
(
SUBMIT ALL GRAPHS MADE by copying and pasting into here
)
4.
Plot the population size for each species by latitude (using the scatterplot option in excel).
You can do all 6
species in 1 graph, but please make sure each line is a different color/symbol. For this graph, you actually
can
connect the dots! When tracking through time or across latitude/longitude, connecting the lines actually makes
sense. Remember, graphs always need: a title, axes labels, axes units, and a legend.
5.
Describe the relationship between population size and latitude for
EACH of the six
species. (Ex: As the
latitude increases, the population density of _____ increases/decreases/etc.) You should have 6 separate
descriptions here.
6
.
Which
TWO
species do you expect should be
most
cold-tolerant based on these data alone?
Support your
answer with data.
7.
Which
ONE
species appears to be the
most
tolerant to environmental variation based solely on the
information provided?
Support your answer with data.
8.
Now add a line of best fit for each species to the graph and describe for
EACH SPECIES
what the numerical
relationship is between latitude and population density (Ex: For every 1 degree increase in latitude, the
population density of ______ increases by _______ individuals). You should have 6 separate descriptions here.
(To fit a “trend line” to the data, right click on the data points in the graph and select the “Add trendline” option
– also click the box that says display equation on chart.
If necessary set the y axis so that the minimum
possible value is 0.
To do this click on the numbers on the y-axis of the graph, then right click on the “format
axis” option. Go to the top and set the minimum axis for a fixed value of 0)
9.
Now make a graph comparing the population sizes of two species you think are
most likely
to compete (hint:
start by graphing only the species that overlap in latitude - there is only ONE correct pair).
Based on these
graphs, which species pairs may be competing for resources and why do you say this?
Remember, merely
overlapping does not mean they compete. For example, do deer and ants compete for resources?
Probably not!
Assume if they compete, one species will likely completely outcompete the other (for this
example).
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10.
Is there any evidence that interspecific competition is limiting the range of pairs of species?
If so, which
ones?
Do you think the data provided are sufficient to allow you to conclude that this is what is limiting the
range of a species?
Explain your answer - even if you say no!
Turn in your completed graphs with your document on
Blackboard by the end of your section! You should have at
least 2 graphs (questions 4 and 9) with the appropriate
labeling.