christamariah8
Mallard Ducks
What is the organism? How does it disperse? What is its global range?
How does it reproduce? How many reproductive units does it create?
Does it have any particular adaptations of note?
1. The organism is a Mallard duck, Anas platyrhyncho (the white one is a Pekin duck that I will not include in this exercise). These ducks disperse by flying and migrating from its northern breeding grounds near Alaska and Canada and flying south for the winter to southern U.S.A, Central America, and the West Indies. However they can also be found globally in Europe, Asia, and the Caribbean. They reproduce sexually after a male follows the female for months, where they then migrate to the breeding grounds together together. Hens lay 6-14 eggs and they care for their precocial young for up to 60 days. However even though the young don‘t rely on the mother, they do usually stick together while they‘re young, while the father leaves once they’re born. Mallard ducks are some of the largest, most common ducks, and males are known for their beautiful coloration.
www.outdoor-michigan.com/Birds.htm
From your observations:
Is it a single or multiple population(s)? Where are the nearest mating members?
How is it distributed (random, clumped, uniform) at each location or over the entire range
of your site?
Why is it located where it is? Do you think the population you are observing is a source
or sink? Where do the offspring of the population you are observing go? Where do
immigrants come from?
2. The population in my observations is a part of what I would say is a single population with the nearest mating members less than a quarter mile away. Over the entire range, the groups are distributed as clumped, with groups of 5-20 ducks in each clump. Within these they are distributed randomly. They are located where they are because they usually stay in groups near their families, although they’re part of the same population, so some flocks may be bigger, and some may be breeding so there are more around. I think the population I’m observing is a source, there is plenty of resources for them to live and increase their population in a proper environment. The offspring stay with the mothers until their down feathers are gone and they can be independent, she then leaves them, but they usually stay in the surrounding area together. Immigrants come from “sinks” or other sources to find resources and mates.
From your brain and calculator:
Plug the average number of offspring created by an individual during one time period, as
well as the number of individuals you estimated, into the geometric population growth
equation. What should the population be in 5 cycles? In 20 cycles? This model is a
hypothesis of sorts. Do you think your population is experiencing this type of growth?
Explain why you think this?
3. With about 50 ducks to start with at my site, after 5 cycles, the population should have increased to 5,000,000 without including any deaths, immigration, etc. After 20 cycles, it would be 50x10^20. My population is absolutely not experiencing this type of growth. So many factors come in to play to decrease the population such as death, disease, immigration, predation, habitat loss, as well as so many don’t produce ten offspring per cycle, some lay only 6. Also many of these ducks are males, so not all 50 ducks are reproducing, only a fraction of them are reproducing, let alone successfully.
From the literature:
Discuss how 2 models or experiments you have studied in class apply to your site. Give
the researcher/year/organism, their question and conclusions. Then summarize in a
sentence or two how those models inform you about your site.
4. One model from the book that applies to my site is the logistic model (Verhulst and Quetelet 1838) that shows the pattern of growth by a population as they begin to deplete environmental resources (pg. 250). It takes an assumed exponential growth rate, but adds the carrying capacity which limits the populations growth. At my site although more could live there, it would eventually reach its maximum occupancy before they would run out of resources and the population would stabilize at a comfortable size where all needs are being met. An example of an experiment was done by Boag and Grant in 1984 on Galapagos finches. They wanted to, “know the influences of the environment on birth and death rates in natural populations“ (pg.252). When there was drought, the population fell and many died from starvation since their food wasn’t growing. When there was excess rainfall the population greatly increased. This allowed them to conclude that there is a positive correlation between the amount of eggs laid and rainfall. This would holds true to my site because they also rely on and eat food that relies essentially on primary producers who rely on the rainfall.
Mallard Ducks
What is the organism? How does it disperse? What is its global range?
How does it reproduce? How many reproductive units does it create?
Does it have any particular adaptations of note?
1. The organism is a Mallard duck, Anas platyrhyncho (the white one is a Pekin duck that I will not include in this exercise). These ducks disperse by flying and migrating from its northern breeding grounds near Alaska and Canada and flying south for the winter to southern U.S.A, Central America, and the West Indies. However they can also be found globally in Europe, Asia, and the Caribbean. They reproduce sexually after a male follows the female for months, where they then migrate to the breeding grounds together together. Hens lay 6-14 eggs and they care for their precocial young for up to 60 days. However even though the young don‘t rely on the mother, they do usually stick together while they‘re young, while the father leaves once they’re born. Mallard ducks are some of the largest, most common ducks, and males are known for their beautiful coloration.
www.outdoor-michigan.com/Birds.htm
From your observations:
Is it a single or multiple population(s)? Where are the nearest mating members?
How is it distributed (random, clumped, uniform) at each location or over the entire range
of your site?
Why is it located where it is? Do you think the population you are observing is a source
or sink? Where do the offspring of the population you are observing go? Where do
immigrants come from?
2. The population in my observations is a part of what I would say is a single population with the nearest mating members less than a quarter mile away. Over the entire range, the groups are distributed as clumped, with groups of 5-20 ducks in each clump. Within these they are distributed randomly. They are located where they are because they usually stay in groups near their families, although they’re part of the same population, so some flocks may be bigger, and some may be breeding so there are more around. I think the population I’m observing is a source, there is plenty of resources for them to live and increase their population in a proper environment. The offspring stay with the mothers until their down feathers are gone and they can be independent, she then leaves them, but they usually stay in the surrounding area together. Immigrants come from “sinks” or other sources to find resources and mates.
From your brain and calculator:
Plug the average number of offspring created by an individual during one time period, as
well as the number of individuals you estimated, into the geometric population growth
equation. What should the population be in 5 cycles? In 20 cycles? This model is a
hypothesis of sorts. Do you think your population is experiencing this type of growth?
Explain why you think this?
3. With about 50 ducks to start with at my site, after 5 cycles, the population should have increased to 5,000,000 without including any deaths, immigration, etc. After 20 cycles, it would be 50x10^20. My population is absolutely not experiencing this type of growth. So many factors come in to play to decrease the population such as death, disease, immigration, predation, habitat loss, as well as so many don’t produce ten offspring per cycle, some lay only 6. Also many of these ducks are males, so not all 50 ducks are reproducing, only a fraction of them are reproducing, let alone successfully.
From the literature:
Discuss how 2 models or experiments you have studied in class apply to your site. Give
the researcher/year/organism, their question and conclusions. Then summarize in a
sentence or two how those models inform you about your site.
4. One model from the book that applies to my site is the logistic model (Verhulst and Quetelet 1838) that shows the pattern of growth by a population as they begin to deplete environmental resources (pg. 250). It takes an assumed exponential growth rate, but adds the carrying capacity which limits the populations growth. At my site although more could live there, it would eventually reach its maximum occupancy before they would run out of resources and the population would stabilize at a comfortable size where all needs are being met. An example of an experiment was done by Boag and Grant in 1984 on Galapagos finches. They wanted to, “know the influences of the environment on birth and death rates in natural populations“ (pg.252). When there was drought, the population fell and many died from starvation since their food wasn’t growing. When there was excess rainfall the population greatly increased. This allowed them to conclude that there is a positive correlation between the amount of eggs laid and rainfall. This would holds true to my site because they also rely on and eat food that relies essentially on primary producers who rely on the rainfall.