DISSERATION RESEARCH:   The consequences of parental investment for other aspects of life history

Do offspring associate with the parent that values them more in biparental fishes?
Research Advisor: Dr. Colette M. St. Mary, Department of Biology, University of Florida

In biparental fishes, parents rarely mate for life, and thus do not share long-term interests. Life-history theory predicts that the parent with lower expected future reproduction will value the current brood more and increase investment in care. A parent, whose partner invests more in offspring, will have the opportunity to reduce its current parental expenditure and consequently increase future reproduction. Thus, parents will likely not invest similarly. Further, fry may benefit from affiliating with the parent who invests more. For instance, during predation events, fry survivorship may be greater in close proximity to the more defensive parent.

This work is funded by an award from the Fisheries Society of the British Isles' Small Research Grant (September 2008), the American Cichlid Association's Guy Jordan Endowment Fund (July 2008), and donations of fish from Ekk-Will Waterlife Resources & Tropical Fish Farm (Gibsonton, FL).

 

The effect of brood reduction on subsequent mate preference in the biparental convict cichlid
Research Advisor: Dr. Colette M. St. Mary, Department of Biology, University of Florida

In biparental species, care by both parents is essential for offspring survival. An individual’s reproductive success depends not only on its own ability to fend off predators, but also on that of its partner. Thus, it is to an individual’s benefit to choose a good parent as a partner. Further, an individual may use the success of the current brood as an indicator of their partner’s parental abilities. We examined the extent to which current brood success or failure affected an individual’s subsequent pairing decisions in the convict cichlid, Archocentrus nigrofasciatus. Pairs were put into one of two treatments: (1) brood size was reduced (free-swimming fry removed with a net) over 4 days in association with exposure to a predator model; or (2) brood size was not changed in association with exposure to a predator model. Approximately 14 days after spawning, the male or the female was placed into a choice-aquarium, where we measured the amount of time spent with the previous partner of known brood success versus an unknown partner. This measurement was used to quantify the mate preference of an individual for a subsequent breeding.

This work was funding, in part, by an award from the American Cichlid Association's Guy Jordan Endowment Fund (August 2007) and donations of fish from Segrest Farms (Gibsonton, FL).

 

GRADUATE RESEARCH 

Managing Risk: male promiscuity as a bet hedging strategy
Principle Investigator: Clare Rittschof, Department of Biology, University of Florida

Using a dynmaic modeling approach, we examined wheather multiple mating in male golden orb weaving spiders, Nephila clavipes, is a bet-hedging strategy.

MUSEUM BASED RESEARCH

Phylogeography & Systematics of the Slender Madtom, Noturus exilis
Principle Investigators: Dr. Rebecca Blanton Johansen, Dept. Biology & Center of Excellence for Field Biology, Austin Peay State University & Dr. Larry Page, Ichthyology, Florida Museum of Natural History, University of Florida

We are examining genetic variation and morphological variation between populations of a species of catfish. I was responsible for collecting morphological, meristic, and pigmentation data from museum specimens.

 

Systematics of the Amphilius sp.
Principle Investigator: Alfred Thomson, Ichthyology, Florida Museum of Natural History, University of Florida

We are describing a species of African catfish, from the Amphilius genus. I am responsible for collecting morphological data from museum specimens.

 

 

FIELD RESEARCH

Parental Investment of free-swimming offspring in Costa Rican cichlids
Collaborators: David Mellor, Department of Ecology, Evolution and Natural Resources, Rutgers University
                       Ronald Coleman, Department of Biological Sciences, California State University Sacramento
                       Rebecca Jordan, Department of Ecology, Evolution and Natural Resources, Rutgers University

We are examining sex differences in offspring defense behavior of two species of Costa Rican cichlids, Neetroplus nematopus and Archocentrus septemfasciatus.

Cichlid egg size evolution in Neotropical rivers
La Selva Biological Station, Costa Rica - January 2005, 2006, 2007, 2008, and 2009
Principle Investigator: Dr. Ronald M. Coleman, Dept. Biological Sciences, California State University Sacramento

To see pictures from the field, click here.

I have been assisting on a long term project examining the relationship between egg size, ecological factors and other life history characteristics. In this system, species that lay small eggs (e.g., Archocentrus septemfasciatus - 1.5mm) tend to spawn in slow backwaters in cervices or caves, while species that lay larger eggs (e.g., Tomochila tuba - 2.6mm) tend to spawn in fast water on the open face of rocks. To understand this phenomenon, we are collecting detailed data on which species spawn where in the river, the size of their eggs and the swimming abilities of young. We have found that large eggs hatch into large offspring and are better at swimming in fast currents on the first day of free-swimming. While small eggs hatch into small offspring and are not able to swim in fast currents on the first day of free-swimming. However, larger eggs also take longer to hatch than smaller eggs, and therefore require longer periods of care. This on-going work is improving our understanding of the tradeoffs involved in the evolution of egg size in fishes, by examining the relationship between ecological factors and life history characteristics.

 

 

UNDERGRADUATE HONORS RESEARCH

Egg size through consecutive spawnings in the convict cichlid
Evolution Ecology of Fishes Lab, California State University Sacramento, June 2004 - May 2005
Research Advisor: Dr. Ronald M. Coleman, Dept. Biological Sciences, California State University Sacramento

I conducted an independent project investigating life history characteristics in biparental cichlid. Female have a finite amount of resources with which to make eggs. This creates a tradeoff between the number of eggs a female can produce and the size of the eggs. Different species resolve this tradeoff differently (e.g., some produce a few large eggs and others produce many small eggs). I was interested in examining whether females of the same species resolve this tradeoff differently through time, when environmental conditions are constant. I spawned fourteen virgin lab-raised Archocentrus nigrofasciatus five consecutive times, under laboratory conditions. I found that the first time a female spawned she laid larger eggs than in subsequent spawnings. I also found that the number of eggs in a clutch increased as female weight increased, and mean egg size was unaffected by female weight. Thus it is likely that the larger size of egg in the first spawnings was due to spawning sequence rather than female size. This result suggests that egg size decisions are complex and likely the product of many conflicting tradeoffs. It will require closer examination to fully understand why eggs are the size they are.

 

 

 

I would like to thank the following people and organizations for their donations and/or funding support:

Christopher Watts, EkkWill Waterlife Resources &

Guy Jordan Endowment Fund Award From

Small Research Grant Award from the Fisheries Society of the British Isles