Abstract Detail

Bryological and Lichenological Section/ABLS

STARK , LLOYD R [1].

Developing a Conceptual Ecological Model for Desiccation Tolerance in Bryophytes: First Steps.

The ecology of vegetative desiccation tolerance (DT) in bryophytes is understudied. The mechanistic paradigm of DT in bryophytes, i.e., constitutive protection coupled with rehydration-induced repair, is shown to be untenable for studies of ecological DT, with issues including nonstandard deacclimation times, within-patch heterogeneity, and a conflation of rate of drying with equilibrating relative humidity (RH). Mechanistic studies have too often ignored the physiological states of hydration, namely hardening and dehardening. In addition, whereas mechanistic studies of DT in bryophytes consider processes, ecological studies of DT consider the effects of desiccation on fitness, with fitness viewed broadly as survival, growth, and reproduction. For example, should a shoot drying event result in 90% tissue mortality, mechanistically the shoot is considered dead. However, if the shoot apex survives, it becomes ecologically significant in terms of survival and regeneration. A model of DT reflecting the physiological states of hydration in mosses is presented, along with an ecological hypothesis termed the “Continuum Hypothesis of DT”: ecological strategies of DT exist along a continuum between highly constitutive and highly inducible. Restated, ecological DT can be viewed along an inducibility gradient. Predictions from this hypothesis include (1) species considered as constitutively protected enlist elements of an inducible response, and (2) within a single species, different life history phases or structures (e.g., protonema, juvenile shoots, adult shoots, embryonic sporophytes, meiotic capsules, shoot apices) may exhibit more than one ecological strategy of DT.

1 - Department Of Biological Sciences, SCHOOL OF LIFE SCIENCES, UNIVERSITY OF NEVADA, LAS VEGAS, NV, 89154-4004, USA

Keywords:
ecological strategy
constitutive desiccation tolerance
inducible desiccation tolerance
bryophytes
hardening
dehardening.

Presentation Type: Oral Paper:Papers for Sections
Session: 23
Location: River Fork/Grove
Date: Tuesday, July 29th, 2014
Time: 9:30 AM
Number: 23003
Abstract ID:265
Candidate for Awards:None