Patera pennsylvanica



Adaptation is closely related to evolutionary biology because adaptation refers to the traits that are acquired, altered, or lost to increase the fitness of the organism and help the organism better adjust to its environment (The Free Dictionary 2012). There has been a large amount of adaptations that have led to what the species Patera pennsylvanica are today, some of which are covered in this section. Due to the lack of specific information about the species Patera pennsylvanica adaptations from other taxonomic levels of Patera pennsylvanica will be analyzed.

Alex Tompa looked at how common calcified eggs are within the order Stylommatophora, the taxonomic order for Patera pennsylvanica (Tompa 2005). It was found that 36 of the 65 families of the order Stylommatophora are either partially calcified or heavily calcified, an advantageous characteristic (Tompa 2005). The benefits of calcified eggs include calcium’s role in mechanical support of the shell and its contents (Tompa 2005). Furthermore calcified eggs enable the embryonic shell to be ready for hatching by providing the embryo with calcium (Tompa 2005). These functions make calcified eggs a terrestrial adaption to many families within the order Stylommatophora (Tompa 2005).

Torsion is a gastropod synapomorphy (ZipcodeZoo 2012). According to Ghiselin, theories by Lang and Naef accurately describe the adaptive importance of torsion by taking into account limpets, the ancestor of gastropods (Ghiselin 1966). Limpets were evolving shells of increased height to the point of instability and a lack of balance, negatively affecting locomotion and respiration which ultimately threatened survival (Ghiselin 1966). Torsion shifts the center of gravity back to a stable point by placing the mantle cavity and the shell on alternate sides, returning balance and stability effectively for organisms to maintain upright and move efficiently (Ghiselin 1966).

The species Patera pennsylvanica is within the informal order Pulmonata (ZipcodeZoo 2012). Barnhart found that Pulmonates have the capability of undergoing periods of dormancy that are capable of withstanding lengthened periods of little food and water (Barnhart 1986). Morphologically, the shells and mantle collar create a waterproof seal, limiting water loss (Barnhart 1986). However the opening to the respiratory system in gastropods known as the pneumostome essentially breaks this seal (Wikipedia 2012), with the amount of time the pneumostome is opened having a directly proportional relationship with water loss (Barnhart 1986). The amount of time the pneumostome is open can be regulated and ultimately reduced by establishing partial pressure differences between the air and lung with oxygen and carbon dioxide and by decreasing metabolic rate (Barnhart 1986).

It is beneficial for ATP production to have the ability to transport oxygen through the circulatory system (van Holde et al. 2001). In the class Gastropoda, hemocyanin is the oxygen carrying molecule (ZipcodeZoo 2012). Before hemocyanin was evolved, photosynthetic production of oxygen placed selective pressure on other organisms to neutralize and even benefit from oxygen (van Holde et al. 2001). Enzymes made up of copper and iron functioned in doing this but as time went on diffusion limited oxygen supply, hindering ATP production (van Holde et al. 2001). The rise of hemocyanin was the evolutionary solution to this problem for gastropods (van Holde et al. 2001). The structure of hemocyanin contributes to its function due to its size and its multiple binding sites (van Holde et al. 2001). The large size of hemocyanin ensures osmotic pressure does not become too high while hemocyanin’s multiple binding sites makes the molecule cooperative, meaning oxygen binds to hemocyanin when needed and oxygen is released from hemocyanin when needed (van Holde et al. 2001). To summarize, hemocyanin is an adaptation that helped gastropods, including Patera pennsylvanica, meet metabolic requirements (van Holde et al. 2001).

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