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
-
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.
-
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:
-
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).
-
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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