mpetracchi's blog

Life on earth is so complex and interconnected it makes little sense to study any individual species when trying to understand the bigger picture. On a daily basis, any given species across the globe interacts with other species within its surrounding habitat. These sorts of interactions are broadly classified as symbiosis, which can then be separated into subcategories of specific interaction types. Some of these interactions observed by scientists include predation, parasitism, commensalism, mutualism, and competition. Every individual, regardless of species, does their best to survive and reproduce by any means necessary and these five relationships are a testament to that. Overall in each case either both, one, or neither species involved in the interaction benefit. In mutualistic relationships, one species provides another with a resource and vice versa, competitive relationships tend to harm both species as neither can reach their full potential resource claim, and predation benefits one species at the complete expense of another.

Species that interact in a given time and place can be defined as a community. Ecologists across the globe study these communities, specifically the type of species, physical environment, and the interaction between them to better understand how these communities work. In order to study a community, a scientist defines the parameters of inclusion. Scientists ask specific questions when looking at a community and including absolutely every organism would be impractical. Therefore parameters are set so only the most important species are included to conduct appropriate research. The subsequent naming of the community is decided by the biological and physical characteristics present. A community found on a mountain may be considered a mountainous community while a coral reef is defined by the biological organism coral. Within a community, every species has a role or niche and can then become grouped further by what it consumes and what consumes it. A group of species who use the same resources is known as a guild and a functional group is a group of species that perform similar tasks. These labels allow ecologists to produce food webs or interaction webs to easily understand the types of relationships found in a community. 

      Similarly, the Egyptians understood the importance of control and rule over their people and to reach a great majority their religious texts fit the bill. Many gods were worshipped in this poly-theistic culture and how better to control the people if the gods they worshipped enforced control. One specific god that fulfilled this role was Horus, a falcon-headed god of the sky. He was often presented next to statues of pharaohs and therefore gave the impression the pharaoh was one with the gods. The idea was that a falcon could fly overhead and watch all of the lands below. Sometimes reaching heights it seemed to disappear and therefore represented by a sun-disc on Horus’ head. “Such a powerful creature was, therefore, like the bull, appropriated by the pharaohs” to maintain control of the people by discouraging any revolts (Attenborough). The pharaoh was essentially a god, and going against the will of the gods would not end well.

      Although the Sumerians may have been treated to violent scenes of public ritual, they did have some freedoms in their society. Their organization gave them a surplus of food, which “allowed many people to pursue occupations other than farming, while still being able to meet their basic needs. These people became artisans, merchants, and craftspeople”(Life in). These occupations could be chosen on their own accords and therefore gave the people the freedom to choose. The freedom to do what they wanted to do in their free time.

In ancient civilizations, exercising control over the masses by the elites ensured their reign and status. These elites accounted for many aspects of daily life, however, not all. Giving the people some freedoms would ensure their reciprocal support to the state, also, controlling every aspect of a person’s life in a civilization so large would be impossible. Civilizations such as Sumer in Mesopotamia and Egypt ruled over their people with this concept in mind.

    Controlling the masses came about through many different approaches. Notably in the fertile crescent was the royal graves at Ur. This archaeological site uncovered just how far the elites in society went to ensure their rule was seen as legitimate and powerful. Within the findings were many sacrificed people dressed in elaborate dresses and jewelry which suggests these killings may have been ritual. However sacred the public event must have been, D. Bruce Dickson argued: “The graves themselves are part of the effort made by Ur’s rulers to establish the legitimacy of their governance by demonstrating their sacred, holy and non-ordinary status” (Dickson). In other words “Accept our power and we will protect you from worse violence” (Dickson). The elites threatened the everyday lives of their commoners as a means to maintain control.

If two species are isolated due to a physical barrier, however, travel between the two sites remains viable the population is said to be a metapopulation. In other words two or more populations spatial separated with some level of interaction. Populations such as these face different challenges and are affected by factors differently to a classic population. Two variables can be measured of a metapopulation that is different from classic populations, C, and E. C is the colonization rate of the various patches of habitable land and E is the extinction rate of the populations. When C is greater than E then the metapopulation can survive for long periods of time. Any other relationship results in the eventual extinction of the population. When determining the relationship a metapopulation has scientists consider two factors. The first is Isolation. The degree to which a habitable patch is isolated from the rest of the patches will affect both the colonization and extinction rate. A highly isolated patch will have a much lower colonization rate due to it being hard to reach or find by immigrating individuals. Simultaneously, the extinction rate will be higher because a small isolated population is more susceptible to extinction events. The other factor as mentioned in the previous sentence is the size of the population at a specific location. 

Plant hormones, also known as phytohormones, act similarly to hormones found in animals. They can be peptides, steroids, or other small molecules that in some way affect responses in a plant. There are many factors hormones influence including growth, germination and cell fate, to name a few. After studying hormones and their pathways, we now know-how hormones originate and what their eventual outcomes can be. A hormone is initially synthesized, using a tightly regulated system, at a specific spot in the plant. The synthesis tends to occur near the areas of use. After synthesis a plant may conjugate the hormone to inactivate and store it for later use instead of having it degraded and needing to produce another later. Once created the hormone needs to be transported to where it will be used. The plant uses both transport through the phloem and xylem, as well as transport proteins between cells. This way the hormone can travel larger distances and cover local patches. Once at the targeted site, a receptor specifically designed for the molecule will bind and activate. The activation causes a signaling chain that eventually reaches an effector which responds to this stimulus. A response could be genomic and induce transcription to produce a change or an activation/ inactivation of pre-existing proteins. 

Scientists observed and quantified similar growth patterns many species on earth follow. Populations of species experience a higher growth rate at lower population densities until they reach a plateau at a carrying capacity. The carrying capacity of a population determines the number of individuals an environment can sustain indefinitely. A logistic growth curve fits the studied phenomena as populations begin exponential and level out. This model only does so much as in real life this tends to not be a perfect match. Populations regularly overshoot their carrying capacity when times are good and population growth rates are positive even after having crossed the figurative line. The environment simply cannot sustain this population over the carrying capacity affecting the species in two ways. Decreased birth rates from less food and possible increased emigration to find suitable ranges. The growth rate therefore decreases and the population drops, possibly undershooting the carrying capacity at which point the cycle may repeat. Populations that over-and-under shoot by very little can be described as dampened oscillations. Other populations with patterns that oscillate greatly, at regular intervals, are called regular fluctuations.

Species on earth usually follow a similar growth pattern which scientists have been able to observe and quantify. In general, a species will experience a higher growth rate when at lower population densities until it reaches a plateau at its carrying capacity. The carrying capacity is the number of individuals an environment can sustain indefinitely. The most basic way to describe this model is through a logistic growth curve. It begins exponential and levels out. However, this is not the full story in real life. What tends to happen is a population will overshoot the carrying capacity when times are good and population growth rates are positive. When this happens the environment imply cannot sustain this population and the species feels the impact via two factors. Decreased birth rates from less food and possible increased emigration to other suitable ranges. The growth rate then decreases and the population may undershoot the carrying capacity at which point the cycle may repeat. Populations that over-and-under shoot by very little can be described as dampened oscillations.

An unfortunate problem some species face is the allee effect of population growth. The trend most observed in the wild is when population density is low for a certain area, the growth rate is high because the environment can sustain more individuals than currently present. However, consider a small population that is very dispersed and therefore partially isolated from each other. When it comes time to breed they may not be able to find a mate in time and therefore not produce any young. This is the allee effect. Low population densities mixed with isolation produces a decreased growth rate. This effect can drive many species to extinction fairly quick as it's hard to recover when a population size becomes so small so fast.

Species on earth usually follow a similar growth pattern which scientists have been able to observe and quantify. In general, a species will experience a higher growth rate when at lower population densities until it reaches a plateau at its carrying capacity. The carrying capacity is the number of individuals an environment can sustain indefinitely. The most basic way to describe this model is through a logistic growth curve. It begins exponential and levels out. However, this is not the full story in real life. What tends to happen is a population will overshoot the carrying capacity when times are good and population growth rates are positive. When this happens the environment imply cannot sustain this population and the species feels the impact via two factors. Decreased birth rates from less food and possible increased emigration to other suitable ranges. The growth rate then decreases and the population may undershoot the carrying capacity at which point the cycle may repeat. Populations that over-and-under shoot by very little can be described as dampened oscillations.

An unfortunate problem some species face is the allee effect of population growth. The trend most observed in the wild is when population density is low for a certain area, the growth rate is high because the environment can sustain more individuals than currently present. However, consider a small population that is very dispersed and therefore partially isolated from each other. When it comes time to breed they may not be able to find a mate in time and therefore not produce any young. This is the allee effect. Low population densities mixed with isolation produces a decreased growth rate. This effect can drive many species to extinction fairly quick as it's hard to recover when a population size becomes so small so fast.

Species on earth usually follow a similar growth pattern which scientists have been able to observe and quantify. In general, a species will experience a higher growth rate when at lower population densities until it reaches a plateau at its carrying capacity. The carrying capacity is the number of individuals an environment can sustain indefinitely. The most basic way to describe this model is through a logistic growth curve. It begins exponential and levels out. However, this is not the full story in real life. What tends to happen is a population will overshoot the carrying capacity when times are good and population growth rates are positive. When this happens the environment imply cannot sustain this population and the species feels the impact via two factors. Decreased birth rates from less food and possible increased emigration to other suitable ranges. The growth rate then decreases and the population may undershoot the carrying capacity at which point the cycle may repeat. Populations that over-and-under shoot by very little can be described as dampened oscillations.

An unfortunate problem some species face is the allee effect of population growth. The trend most observed in the wild is when population density is low for a certain area, the growth rate is high because the environment can sustain more individuals than currently present. However, consider a small population that is very dispersed and therefore partially isolated from each other. When it comes time to breed they may not be able to find a mate in time and therefore not produce any young. This is the allee effect. Low population densities mixed with isolation produces a decreased growth rate. This effect can drive many species to extinction fairly quick as it's hard to recover when a population size becomes so small so fast.