Mating System and Effective Population Size of the Overexploited Neotropical Tree (Myroxylon peruiferum L.f.) and Their Impact on Seedling Production

Abstract

The reproductive system of a tree species has substantial impact on genetic diversity and structure within and among natural populations. Such information, should be considered when planning tree planting for forest restoration. Here, we describe the mating system and genetic diversity of an overexploited Neotropical tree, Myroxylon peruiferum L.f. (Fabaceae) sampled from a forest remnant (10 seed trees and 200 seeds) and assess whether the effective population size of nursery-grown seedlings (148 seedlings) is sufficient to prevent inbreeding depression in reintroduced populations. Genetic analyses were performed based on 8 microsatellite loci. M. peruiferum presented a mixed mating system with evidence of biparental inbreeding (t^m-t^s = 0.118). We found low levels of genetic diversity for M. peruiferum species (allelic richness: 1.40 to 4.82; expected heterozygosity: 0.29 to 0.52). Based on Ne(v) within progeny, we suggest a sample size of 47 seed trees to achieve an effective population size of 100. The effective population sizes for the nursery-grown seedlings were much smaller Ne = 27.54-34.86) than that recommended for short term Ne ≥ 100) population conservation. Therefore, to obtain a reasonable genetic representation of native tree species and prevent problems associated with inbreeding depression, seedling production for restoration purposes may require a much larger sampling effort than is currently used, a problem that is further complicated by species with a mixed mating system. This study emphasizes the need to integrate species reproductive biology into seedling production programs and connect conservation genetics with ecological restoration.

Mating Systems of Single Families and Population Genetic Diversity of Endangered Ormosia hosiei in South China

“…The outcrossing rates at the population level and among individuals within each population were similar between the two populations of O. hosiei . The multi-locus outcrossing rate obtained in the present paper are comparable to those reported for other leguminous species with different molecular markers as well as for different levels ( Table S4 ) [ 2 , 4 , 13 , 14 , 15 , 16 , 41 , 51 , 52 , 53 , 54 ]. The general trend observed is that Leguminous species, whether at the individual, population, species, or genus level, displayed a predominantly outcrossing system, with high t m estimates.…”

“…The effective number of pollen donors (Nep) per family suggests that few paternal parents contributed pollen to each progeny in the analyzed generation, indicating inbreeding or biparental inbreeding. The correlated mating found in the O. hosiei fragmented population may be associated with: (1) few plants flowering in the year of seed collection and low population density of the species, at three individuals per hectare (Investigated by author); few plants flowering and low population density is assumed to be related to reducing pollen diversification [ 5 , 54 ], leading to an increase mating between a limited number of individuals; (2) the limited number of maternal trees sampled, including trees that are very close to each other ( Figure 1 ), resulting in increased mating between a limited number of individuals.…”

Effective population size remains a suitable, pragmatic indicator of genetic diversity for all species, including forest trees

“…Ne/Nc values for available tree species shown as insert; these are in agreement with estimates from seed orchards e.g. 0.14-0.17 in Myroxylon peruiferum,(Silvestre et al, 2018). Note: the top ten and the bottom ten values fromHoban et al (2020) were excluded for visualizing the histogram, although these values were retained for quartiles estimation.…”

Microsatellites are important for forest genetic resources conservation in Brazilian biomes

“…Eight microsatellite loci used to study the reproductive system and genetic diversity in Myroxylon peruiferum revealed a mixed reproductive system in this species with evidence of biparental inbreeding at the rate of 0.118. Genetic diversity was low (allelic richness = 1.40 -4.82; H E = 0.29 -0.52) and the effective sizes for seedlings were much lower (Ne = 27.54 -34.86) to those recommended for short-term conservation (Ne ≥ 100) (Silvestre et al 2018).…”