January 29, 2014
GGR 305 Lecture Notes
General Rules of Distribution and Abundance Distribution of scissor tailed flycatcher, only in the
black blob, geographic distribution (has an outline of where they are), each circle is a census or
inventory and the size is the relative abundance, more information of the species and how many
in the region and geographical range.
- Comments we can make? High number is around other high numbers, towards the
centre and southern it is more abundant and outwards they become less abundant
expect for the southern and has high abundance rates up to the edge, could be due to
no studies being there, gulf of mexico and a physical barrier that’s affecting its
distribution or limiting its distribution
- Has a clumped nature and high abundance is in the centre and to the edges its in lower
What are the Limiting Factors?
Any factor that makes it difficult for an organism to live, grow and reproduce, can be stressful
that they can’t reproduce and sustain a population there
-physical: temperature, wetness, light
-Biological: competition, predation and mutualism
- how they all play out
-Eury(wide) topic: ecologically tolerant, survive a wide range of conditions, not many physical
-Sten(narrow)tropic: lots of physical factors that affect their living
-land vs water, birds found and other birds not found
-Can be a radiant, centre has conditions as optimal and temp can be optimal in order for specie
to survive and will be in high abundance. Move away and entre into zones of physiological
stress, can survive but not thriving (optimal) and struggling from less conditions and lower
populations. Conditions can be so stressful that specie becomes diminished and some
optimum temp and has the least stressful population, specie can survive and not optimal.
-E.g. bird (flycatcher) condition is optimal in the middle and the surroundings can survive but
not optimal and lower levels of populations
-the way we draw species distribution is based on our knowledge January 29, 2014
Temperature and the Eastern Phoebe
- Can’t survive in very cold temperature eg. Plant needs photosynthesis to survive, birds
or mammals temp also important and for metabolic properties.
- Identifying is a limiting factor, we have cold in winter and warm in summer, cold night,
warmer in day, limiting factor can be challenging
- E.g. eastern Phoebe, dotted line = places that have a minimum Jan temp of -4 and can’t
survive there, there Northern geographic extent corresponds to the -4 degrees Celsius.
Too cold is a limiting factor along Northern boundary
- Cactus black dots represent a location of where they are present, can survive in short
periods of cold and if it’s in the cold for too long it won’t survive, in the South, won’t go
cold for a long period of time. Black dots are contradicting because can’t survive for
more than 24 hours of cold. But it’s the young cactus that’s sensitive and won’t survive.
Found under Nurse tress (also in desert and are short found in the grey areas and have
a small cactus, creates a micro climate and its warmer and the young can survive the
below freezing conditions) grow so big and outcompete and take over the nurse tree and
can then survive the cold temps and populations that have established over time and the
microclimate effect can survive in the lower temperatures. The out in the open trees
don’t survive and it would die. Low temps are a limiting factor and can expend with a
micro climate and to vulnerable temps.
Finding Temperature Range
- Minimum or the whole, length of period, maximum temp it reaches, too hot for too long
needs to sustain heat
- Differ species of the plant, planted the species in a long grow (narrow bed of soil) heated
and cooled the soil to cold, moderate and high, how many days it took the seeds to
germinate (shown in the graphs) long bed of seed and the temps along the bottom.
and y axis has how many days it took to germinate. Low point is the quickest to
germinate and the moderate temp was the most successful. Temp low took longer and
hotter no seeds germinated at very high temps.
- Other specie has a higher optimum range.
Temperature: Mammals and Birds
- Bergmans Rules: for closely related mammals and birds, the larger form occur at higher
- Fined Tuned Rule: body size related to climate, cooler is larger and warmer is smaller
forms and is due to larger individuals has a lower __ to surface area
- Holes in this: larger has higher food requirements to survive, more energy and more
surface area losing more heat, larger forms in colder nothing to do with climate
- WHY??? second week and latitude gradient of diversity: higher by equator and lower
away from the equator, fewer species in total and more competition and for food and
more advantage to being smaller and lower food requirements. January 29, 2014
- Study on wood rats size of the individual had nothing to do with how cold it was but how
warm it was, and what they found was that larger wood rats are more stressed in
warmer temps and do better than to be large, found in the fossil record and by looking at
it today, cooler= larger, warmer = smaller, reaction to how things get and for max July
temps and body size of wood rats so Bergmans Rule still holds.
- Allen’s Rule: cold environments have shorter extremities relative to body mass
- Fox (artic) vs South west
- Hares vs foxes and had to find others to match this idea beyond few discussed example
- Gloger’s Rule: coloration of related forms is correlated with humidity, why? Lower levels
humidity = lighter and higher level humidity = darker eg. field mice WHY??? Humid
areas has better blending in with dark vegetation and less likely to be eaten vs Leaves
not dark and want to blend in the arid vegetation or environments
- Predation rates higher for those not part of the environment
- Xerophytes (thrive) Mesophytes (medium) , and hydrophytes(need it)
- Needs water and looks to certain mammals and often have evolved mechanisms to
minimize these conditions
- Talking about plants arid and wet areas and adaptations
- Xerophytes “Tree of Life” in Africa and often depicted and has a wide trunk. Thrive in
arid areas and the trunk stores lots of water and when go through dry and the water in
the trunk keeps them alive and mesquite bushes have long tap roots to find little bits of
- Mangroves went environments and have adapted roots that are above ground and
handle the very wet conditions they grow in
- Can vary across spacious scales, humidity and how it varies across regions, can vary