デモグラファー会議

The 3rd Meeting of Power Demography


Date: Nov. 20 (Fri), 2020 13:00–17:30.
Place：Online meeting. (The registration is necessary).

For registration:
1) The registration URL of Google Form: https://docs.google.com/forms/d/e/1FAIpQLSeg_EHTE5CAlONMdJNPgEzaqASQ3SJpBTsEkgTpLta-9waW5Q/viewform
It takes only one minute to fill e-mail address, name and affiliation.
2)　We send the Zoom URL to the registrated e–mail address on Nov. 17 (Tue.).


SYMPOSIUM
Organizer：Richard Shefferson（Univ. of Tokyo), Tak Takada (Hokkaido Univ.)

Demography is a wide academic field that studies plants and animals including human. This symposium is organized as a kind of salon not only to present the new theories, methods and topics but also to learn the basic theories and methods.

Speakers and titles:
Tak Takada (Hokkaido Univ.) Introductory talk
Hiroshi Tomimatsu (Yamagata Univ.)　　Population biology of a forest herb Trillium camschatcense in anthropogenically fragmented and geographically peripheral habitats. Abstract
Fumiko Ishihama (NIES)　Estimating the extinction risk of "immortal" tree -simulation analysis using a shoot-dynamics matrix model. Abstract -
Hiroyuki Yokomizo (NIES)　Inter-stage flow matrices: a new population statistic derived from life history matrices Abstract
Richard Shefferson (Univ. of Tokyo)　Addressing the importance of individual history on population dynamics with R package Lefko3. Abstract


Questions and registration：Tak Takada e-mail: takada[at mark]ees.hokudai.ac.jp


Abstracts:
Tomimatsu's abstract: Many plant species currently exist in fragmented populations of different sizes, while they also experience climate variability. However, our understanding of how plant populations differentially respond to such micro- and macro-environmental factors is still limited. Here I will present our research that has been conducted using a forest herb, Trillium camschatcense, from two different perspectives: (1) demographic response of populations to habitat fragmentation and annual climatic variability and (2) a dissection of abundant-center distribution along a latitudinal gradient.

Ishihama's abstract: Although mortality is an essential parameter in describing population dynamics, it is difficult to estimate mortality in long-lived woody and clonally-grown herbaceous species because individual mortality is observed so infrequently, as if the individual "never dies". However, "birth and death" of shoots which compose an individual may be observable in some cases. We present a study to estimate the effects of deer herbivory and the effects of conservation measures on the endangered plant Paliurus ramosissimus by using a matrix model based on shoot dynamics that can be applied to plants composed of physiologically integrated shoots.

Yokomizo's abstract: Population metrics such as population growth rates and elasticities are derived from population matrices constructed from field survey data such as survival rates and fecundity. Those statistics have been useful in understanding the ecological characteristics of various organisms. We have developed a new statistic, inter-stage flow matrix. The sum of the elements of the inter-stage flow matrix is equal to population growth rate. Inter-stage flow matrices enable us to understand how much each individual transition between stages contributes to population growth rates. The inter-stage flow matrices can be a new tool to uncover the ecological characteristics of organisms. In this talk, we will introduce a study that used COMPADRE Plant Matrix Database to determine inter-stage flow matrices to reveal the ecological characteristics of reproduction, growth, and stasis of each functional group classified by life history.

Shefferson's abstract: Population projection models make a number of important assumptions, but chief among these is that vital rates in any given time period are only dependent on the state of the individual in that time interval. This assumption leads to predicted population dynamics that are unaffected by any but the most immediate of life history costs and vital rate correlations. I introduce an R package, lefko3, with a series of methods that create historical matrices, as well as their standard, ahistorical counterparts. These methods can be applied to “raw” projection models, function-based projection models, and even integral projection models. I also show an example illustrating the impacts of individual history on population dynamics.