Evaluating restoration outcomes through assessment of pollen dispersal, mating system, and genetic diversity

Abstract

Ecological genetics can provide a novel contribution to assessing the achievement of restoration objectives. We used paternity assignment to infer realized pollen dispersal within, and pollen immigration into, a restoration population of Hakea nitida, a common near-coastal shrub or small tree in southwest Australia. We compared mating system parameters and genetic diversity with a nearby remnant reference population and assessed genetic divergence among the restoration and reference populations. We found realized pollen dispersal events closely tracked the frequency distributions of the distances between all plants within the restoration focus area. Mean realized pollen dispersal distance (359 m) approached the mean of the distances between all plants (407 m), far exceeding mean nearest neighbor distance (12 m). Maximum realized pollen dispersal distance (869 m) approached the maximum distance between all plants in the study area (1,033 m). Pollen immigration into the restoration study area was limited (4%). The mating system revealed moderate outcrossing rates (t m = 0.861 restoration and t m = 0.745 reference population), with significant and similar biparental inbreeding (t m − t s = 0.180, t m − t s = 0.186) but greater correlated paternity (r pm) in the restoration (0.519) than in the reference (0.188) population. Genetic divergence among the restoration and reference remnant population was moderate (F ST = 0.094, D ST = 0.239). Patterns of pollen dispersal and mating system parameters imply the attraction of pollinators within the restoration population as a key factor in progressing towards the establishment of self-sustaining populations.

Plant mating system dynamics in restoration: a comparison of restoration and remnant populations ofHakea laurina(Proteaceae)

“…This degree of divergence may be a result of seed sourcing from, or that included, more geographically distant populations than those assessed here as reference populations. A similarly greater degree of genetic divergence has been observed between a restoration population and the proposed remnant seed source population of H. nitida for the Peniup site (Millar et al 2020a).…”

“…A similarly greater degree of genetic divergence has been observed between a restoration population and the proposed remnant seed source population of H . nitida for the Peniup site (Millar et al 2020 a ).…”

“…Hakea laurina was chosen as it occurs at two restoration sites, where it is reproductively mature, affording some replication of analyses, and at which similar studies have been conducted on other woody perennial species (Millar et al 2019a(Millar et al , 2019b(Millar et al , 2020a(Millar et al , 2020b. We assessed if effective plant-pollinator interactions, mating system dynamics and genetic diversity have been established in restored populations.…”

Genetic assessment of the value of restoration planting within an endangered eucalypt woodland

“…Our study of the population genetics of natural and revegetated Eucalyptus melliodora populations in WNP is one of the few studies that assess the genetics of woodland tree restoration by comparing the genetic structure of revegetated stands to both paddock trees and intact natural stands (e.g. 7 ). We found that at a broad level, paddock trees and surrounding natural stands form comparably diverse and well-connected populations; moreover, the 30-year old Warrumbungle NP restoration program has been largely successful in adding genetically diverse stands derived from locally sourced seeds.…”

“…As a result, trillions of dollars are spent on ecological restoration and revegetation planting programs each year to restore biodiversity to degraded landscapes 1 – 3 . The goal of restoration is to create a self-supporting ecosystem that is resilient to adversity 4 , but the effectiveness of ecological restoration programs is dependent upon a suite of population genetic issues that influence the success of ecological restoration and revegetation planting programs 5 – 7 . First, the level of population subdivision among remnant or revegetated populations has implications for the level and distribution of genetic diversity, and the likelihood that restoration will exacerbate inbreeding or outbreeding and may produce inbreeding or outbreeding depression 8 – 11 .…”