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TCS 2008 Grants

Recruitment dynamics of Zamia obliqua populations and implications for management and conservation

Cristina López-Gallego clopezgallego(at)gmailcom
Biology Institute, Universidad de Antioquia & Research associate MBC

Juan Santiago Zuluaga juazulu(at)gmail.com
Corporación para Investigaciones Biológicas

Organization:

CORPORACION PARA INVESTIGACIONES BIOLOGICAS (CIB)
Carrera 72A # 78B-141, Medellín, COLOMBIA
Duration of the Project: 12 months
Total Budget $8400
Total requested to TCS $2550
Total requested to MBC $2350
Total shared by CIB $3500

PROJECT ABSTRACT

Population viability of many tropical long-lived plants depends on adult survival and recruitment ability. Little is known about variation in recruitment rates between individuals, and the factors associated with fecundity and successful recruitment in populations of cycads. The main goal of this project is to explore the relative contribution of adults to population recruitment in two populations of Zamia obliqua with contrasting individual distribution, and to evaluate environmental and other factors potentially associated with the recruitment success of individuals in these populations. To this end, we will sample all individuals in the populations and use molecular markers to estimate family relationships among them and establish parents and their relative contribution to recruitment. In addition, we will explore the effects of environmental factors on the recruitment success of individuals in the populations. Detailed information about the recruitment dynamics of populations would be valuable for population management for conservation and potential sustainable use. In particular, we expect to contribute to an important aspect for understanding the demographic dynamics of cycad populations and to provide useful recommendations for the potential exploitation and propagation of the species in local community nurseries.

PROJECT DESCRIPTION

Research rationale and justification

Population viability of many rainforest tropical long-lived plants seems to depend critically on adult survival and the recruitment ability of adults in the population. Nevertheless, variation in the contribution of adults to recruitment is widespread in natural populations of plants. Variation in adult fecundity and recruitment rates would result in a differential contribution of individuals to population regeneration. This variation in fecundity, germination, and seedling survival rates among individuals could have environmental and genetic components. Exploring the factors associated with variation in the recruitment ability of individuals in the populations would therefore provide information about crucial processes affecting population viability. Furthermore, detailed information about individuals and factors contributing to successful population recruitment would be valuable for population management for conservation and for the potential use of population in sustainable ways.

Little is now about factors affecting the recruitment dynamics and potential variation in recruitment rates in populations of neotropical cycads. The main goal of this research will be to explore in detail the recruitment dynamics of populations of Zamia obliqua in the Chocó regio of Colombia to identify factors crucial for population persistence and to use this information for population management and potential use by local communities. To that end, we will explore in detail the relative contribution of adults to the recruitment of two populations with contrasting individual distribution and evaluate genetic and environmental factors potentially associated with the recruitment success of individuals in these populations. Based on information available in the scientific literature for other long-lived tropical plant species and our own field observations, our hypothesis is that a relative small number of adults contribute disproportionably to population recruitment (i.e. the production of seedlings), and that increased recruitment ability of these individuals could be associated with their establishment in favorable environments. In addition, we hypothesize that seeds produced by the few highly successful adult individuals in the populations can establish (germinate and have high seedling survival) themselves in a variety of environments (i.e. genetic effects are more important than environmental effects in seedling establishment).

Project objectives

  1. Examine the genetic composition of the seedlings and juveniles in two populations to establish the number of families present in the recruits, predict the potential number of parents contributing to population regeneration, and identify potential factors associated with differences in recruitment ability among adults.

  2. Explore potential differences in seedling establishment among individuals from different families (with different parents) and the role of environmental factors versus genetic factors (the ‘family’ effect) on the successful recruitment of seeds into the seedling and juvenile stages.

Methods

We will sample all non-adult and adult individuals present in two populations of Zamia obliqua in the region of Cabo Corrientes in the Chocó Province of Colombia (a biodiversity hotspot). All individuals in these populations have been permanently marked, are mapped spatially, and add up to ca. 400 individuals. Both populations are located in the understory of relatively undisturbed rainforest, but differ on individual density and distribution. We will collect leaf samples for genetic analyses from all individuals in the populations and perform environmental measurements on adults and recruits during a first field trip to the population localities. After 10 months, we will sample the populations in a second field trip to record seedling/juvenile mortality and determine potential associations between survival rates and environmental factors. Specifically, for each objective we will use these type of analyses:

  1. We will use molecular markers (potentially microsatellites developed for other Zamia species, otherwise AFLPs) to estimate relatedness coefficients among seedlings and juveniles, and genetic analyses to explore the genealogy of each population to identify the number of families and the potential number of parents contributing to recruitment. Then, using parentage analyses, we will determine the identity of parents for families present in the recruits and compare the relative contribution of adult individuals into the regeneration. Once the relative contribution of parents to population recruitment has been hypothesized, we will explore whether the relative contribution to recruitment by adults is associated with their establishment in advantageous environments (for example site with higher light availability, lower probability of desiccation, etc).

  2. We will test for associations between seedling establishment and environmental factors at a detailed spatial scale, by monitoring seed germination (if enough seeds are available in the natural populations) and seedling survival during 10 months. Then, we will contrast genetic effects (effects due to shared parents) and environmental effects on seedling establishment by comparing individual performance (germination and seedling survival) among families and in relation to the environment (light environment and soil properties mainly).

HOW THE PROJECT FITS THE INTERESTS OF THE CYCAD SOCIETY

We expect to provide detailed information about the recruitment dynamics of Zamia obliqua populations in their natural habitat, particularly to explore the relative contribution of adults into the recruits and the factors that may be associated with recruitment success in these populations. This information would contribute to our understanding of the processes that are crucial for population viability of cycad populations. We plan to keep monitoring fecundity, recruitment, and survival rates in the studied populations, and to use the information generated by this project, a previous project funded by TCS on these populations, and other research efforts, to use population models to evaluate conservation, management, and potential exploitation strategies for the populations of Z. obliqua in the Chocó region of Colombia. In particular, we expect to continue generating useful biological information to develop adequate strategies for the local communities to propagate cycads in a local community nursery. These short- and long-term objectives addressing the needs for detailed biological information to support conservation and management strategies for cycad populations are directly related to the main goals for research and conservation of The Cycad Society.

TIMETABLE FOR THE PROJECT

The project will be carried out in two phases:

First phase (6 months): During a first field trip, we will collect leaf samples for genetic analyses (for both populations, i.e. for about 400 individuals). In addition, we will perform detailed environmental measurements on all individuals in both populations. In the laboratory, we will standardize the protocols for genetic analysis and carry out the analyses for one of the populations (ca. 200 individuals). This first phase addresses objective 1 of this project and funding for this phase is being requested to TCS.

Second phase (6 months): We will continue with genetic analyses, using the individuals of the second population (ca. 200 individuals), and monitor individual survival in the populations in a second field trip. This second phase will also contribute information for objective 1, and will generate the data to address objective 2 of this project.

DETAILED BUDGET FOR THE PROJECT

The project will be carried out in two phases, which can be developed independently (and produce independent results, for project objectives 1 and 2). Funding for the first phase is being requested to The Cycad Society (TCS), and funding for the second phase in being requested to the Montgomery Botanical Center (MBC).

Other sources from which funds are currently being sought for the project:

- Montgomery Botanical Center

Total budget of the project:

Total requested to TCS $2550
Total requested to MBC $2350
Total shared by CIB $3500

GRAND TOTAL $8400

* This budget item includes expenses for lodging, food, and for some days, a field assistant.

Click here for full proposal


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This page was updated on Sunday, 13 June 2010.